JP7734690B2 - Irradiation pattern for measuring object depth - Google Patents

Description

The present invention relates to a detector and a method for determining the position of at least one object. The invention further relates to various uses of the detector device. The device, method and use according to the invention can in particular be employed in various fields, for example in photography, documentation or technical purposes, such as digital photography or video photography for everyday life, games, traffic technology, production technology, security technology, art, medical technology or science. Furthermore, the invention can in particular be used for scanning one or more objects and/or for scanning scenes, such as for generating depth profiles of objects or scenes, for example in the fields of architecture, metrology, archaeology, art, medicine, engineering or manufacturing. However, other applications are also possible.

Depth from Photon Ratio (DPR) technology enables reliable distance measurements with reduced computational requirements, particularly reduced processing power, even in environments where biased light sources or reflective measurement objects cause multiple reflections. For example, WO 2018/091640 describes a detector for determining the position of at least one object. The detector includes at least one transfer device having at least one focal length responsive to at least one incident light beam propagating from the object to the detector; at least two optical sensors, each having at least one light-sensitive area, each designed to generate at least one sensor signal in response to illumination of its respective light-sensitive area by the light beam; and at least one evaluation device configured to determine at least one longitudinal coordinate z of the object by evaluating a quotient signal Q from the sensor signals. The detector is adapted to determine the longitudinal coordinate z of the object in at least one measurement range, regardless of the object size in the object plane.

However, despite the achievements of DPR technology, technical challenges remain.

For distance determination using DPR techniques, a system with a monocamera can be used in combination with a projector that projects a laser point pattern or grid onto the scene. Each point is evaluated, and the distance determined from it. The distance determined with DPR techniques can provide a distance estimate for each laser point and can be refined by triangulation with respect to the known positions of the camera and projector. To calculate the triangulation, a so-called correspondence problem must be solved. The correspondence problem describes the assignment of detected laser points and their location in the projected pattern. Knowing this assignment, the distance can be determined by triangulation. However, DPR evaluations may be so noisy that the correspondence problem cannot be solved unambiguously due to the high point density of the laser point pattern. Specifically, the solvability of the correspondence problem may depend on the distance of the laser points along the epipolar line.

A further challenge with DPR technology is that the area, shape, and 2D intensity profile of the reflected beam spot vary confoundingly when the reflective objects in the imaged scene are unknown. DPR analyzes the response of reflective objects when exposed to individual laser beams. As a result, properties such as the area, shape, and 2D intensity profile of the reflected laser spot depend primarily on the reflector. Analyzing the information provided by these laser spot properties can help identify the type of material that reflected the spot, thereby achieving greater accuracy in estimating the distance between the reflective object and the image sensor or laser beam projector. However, different materials at different distances from the image sensor or laser beam projector can produce nearly identical combinations of laser spot properties, making it difficult to identify the material of the reflecting object and estimate the distance to the projector or camera.

Another difficult problem with current DPR technology is estimating the orientation of a reflecting surface.

A further such challenge is the difficulty of analyzing laser spots that are reflected by sharp edges, when part of the laser spot is reflected on one side of this sharp edge and another part is reflected on the other side of the edge.

WO2018/091640

It is therefore an object of the present invention to provide an apparatus and method that addresses the above-mentioned technical problems of known apparatus and methods. Specifically, it is an object of the present invention to provide an apparatus and a method using DPR technology that are capable of determining the position of an object in space with improved accuracy, preferably with low technical effort and low demands in terms of technical resources and costs.

This problem is solved by the present invention with the features of the independent patent claims. Advantageous developments of the invention, which can be realized individually or in combination, are presented in the dependent claims and/or the following description and detailed embodiments.

In a first aspect of the present invention, a detector for determining the position of at least one object is disclosed.

As used herein, the term "object" refers to any object, particularly a surface or region, that is configured to at least partially reflect at least one light beam incident on the object. The light beam may originate from a projector that illuminates the object, and the light beam is reflected or scattered by the object.

As used herein, the term "position" refers to at least one item of information related to the position and/or orientation of an object and/or at least a portion of an object in space. The at least one item of information may therefore refer to at least one distance between at least one point on the object and at least one detector. The distance may be a vertical coordinate or may contribute to determining the vertical coordinate of the point on the object. Additionally or alternatively, one or more other items of information related to the position and/or orientation of the object and/or at least a portion of the object may be determined. As an example, at least one horizontal coordinate of the object and/or at least a portion of the object may further be determined. Therefore, the position of an object may refer to the vertical coordinate of the object and/or at least a portion of the object. Additionally or alternatively, the position of an object may refer to at least one horizontal coordinate of the object and/or at least a portion of the object. Additionally or alternatively, the position of an object may refer to at least one directional information of the object, indicating the orientation of the object in space.

The detector is:
at least one projector for illuminating an object with at least one periodic illumination pattern, said illumination pattern comprising a plurality of illumination features, said illumination features being spatially modulated; and
at least one sensor element having a matrix of light sensors, each having a light-sensitive area, each light sensor designed to generate at least one sensor signal in response to illumination of its respective light-sensitive area by a reflected light beam propagating from the object to the detector, said sensor element being configured to determine at least one reflected image;
at least one evaluation device, said evaluation device being configured to select at least one reflection feature of said reflection image, said evaluation device being configured to determine at least one longitudinal coordinate z of said selected reflection feature of said reflection image by using a depth from photon ratio technique by evaluating a combined signal Q from said sensor signals;
Including,
The illumination features are patterned illumination features, each of the patterned illumination features including a plurality of sub-features, and/or the illumination features are arranged in a periodic pattern equidistant in rows, each of the rows of the illumination features having an offset, and the offsets of adjacent columns being different.

As used herein, the term "projector," also referred to as an optical projector, refers to an optical device configured to project at least one illumination pattern onto an object, specifically onto a surface of the object. The projector may include at least one light source, also referred to as an illumination device or illumination source, configured to generate at least one light beam. The projector may be configured to generate at least one pattern and project the pattern toward at least one surface or scene containing the object. The projector may be configured such that the illumination pattern propagates from the projector, particularly from at least one opening in the projector housing, toward the object. The projector may be configured to generate and/or project a point cloud; for example, the projector may include at least one digital light processing (DLP) projector, at least one LCoS projector, at least one laser source, at least one array of laser sources; at least one light emitting diode; or at least one array of light emitting diodes. Additionally, additional illumination patterns can be generated by at least one ambient light source.

As used herein, the term "pattern" refers to any known or predetermined arrangement that includes at least one arbitrary shaped feature. A pattern can include at least one feature, such as a dot or symbol. A pattern can include multiple features. A pattern can include a periodic or aperiodic arrangement of features. As used herein, the term "illumination pattern" refers to a pattern that illuminates an object. As used herein, the term "illumination feature" refers to at least one arbitrary shaped feature of the illumination pattern. The illumination pattern can include at least one pattern selected from the group consisting of: at least one point pattern, particularly a pseudo-random point pattern; a random point pattern or a quasi-random pattern; at least one Sobol pattern; at least one quasi-periodic pattern; at least one pattern including at least one known feature; at least one regular pattern; at least one triangular pattern; at least one hexagonal pattern; at least one rectangular pattern; at least one pattern including convex uniform tiling; at least one line pattern including at least one line; or at least one line pattern including at least two lines, such as parallel or intersecting lines. For example, the projector can be configured to generate and/or project a point cloud. For example, the projector can be configured to generate a point cloud such that the illumination pattern can include multiple point features.

The projector may be configured to generate multiple illumination patterns, each including multiple illumination features. The projector may be configured to project two, three, four, five, or more illumination patterns, each including multiple illumination features. The illumination patterns may differ in one or more of the following: number of illumination features, arrangement of illumination features, shape of illumination features, wavelength of illumination features, intensity of illumination features, and aperture angle.

The projector may include at least one transfer device, in particular at least one diffractive optical element, configured to generate an illumination pattern from at least one light beam generated by a laser source. The term "transfer device", also referred to as "transfer system", may generally refer to one or more optical elements configured to modify a light beam, such as by changing one or more of the beam parameters, width, or direction of the light beam. The transfer device may specifically include one or more of the following: at least one lens, e.g., at least one lens selected from the group consisting of at least one adjustable-focus lens, at least one aspherical lens, at least one spherical lens, and at least one Fresnel lens; at least one diffractive optical element; at least one concave mirror; at least one beam deflecting element, preferably at least one mirror; at least one beam splitting element, preferably at least one of a beam splitting cube or a beam splitting mirror; or at least one multi-lens system.

The transfer device may have an optical axis. Specifically, the detector and the transfer device share a common optical axis. As used herein, the term "optical axis of the transfer device" generally refers to an axis of mirror symmetry or rotational symmetry of a lens or lens system. The optical axis of the detector may be a line of symmetry of the detector's optical configuration. The detector has at least one transfer device, preferably at least one transfer system having at least one lens. The transfer system may, for example, include at least one beam path in which the elements of the transfer system in the beam path are arranged rotationally symmetrically with respect to the optical axis. Note that, as outlined in more detail below, one or more optical elements arranged in the beam path may be off-center or tilted with respect to the optical axis. However, in this case, the optical axis may be subsequently defined, such as by interconnecting the centers of the optical elements in the beam path, e.g., by interconnecting the centers of the lenses; in this context, the optical sensor is not counted as an optical element. The optical axis may generally refer to the beam path. There, the detector may have a single beam path along which the light beam travels from the object to the light sensor, or it may have multiple beam paths. As an example, a single beam path may be provided, or the beam path may be divided into two or more partial beam paths. In the latter case, each partial beam path may have its own optical axis. The light sensors may be located on a single and identical beam path or partial beam paths. Alternatively, however, the light sensors may also be located on different partial beam paths.

The transfer device may form a coordinate system in which the longitudinal coordinate l is the coordinate along the optical axis and d is the spatial offset from the optical axis. The coordinate system may be a polar coordinate system in which the optical axis of the transfer device forms the z-axis and distance and polar angle from the z-axis can be used as additional coordinates. Directions parallel or anti-parallel to the z-axis can be considered longitudinal directions, and coordinates along the z-axis can be considered longitudinal coordinates z. Any direction perpendicular to the z-axis can be considered horizontal directions, and polar coordinates and/or polar angles can be considered horizontal coordinates.

As used herein, the term "beam" generally refers to a collection of light rays. Hereinafter, the terms "light ray" and "beam" are used synonymously. As further used herein, the term "light beam" generally refers to a quantity of light, specifically a quantity of light traveling in essentially the same direction, including the possibility that the light beam may have an expansion or divergence angle. A light pulse may include at least one beam profile. A light beam may have a spatial extent. Specifically, a light beam may have a non-Gaussian beam profile. The beam profile may be selected from the group consisting of a trapezoidal beam profile; a triangular beam profile; and a conical beam profile. A trapezoidal beam profile may have a plateau region and at least one edge region. A light beam may be a Gaussian light beam or a linear combination of Gaussian light beams. As used herein, the term "beam profile" relates to the spatial distribution of the intensity of a light beam, particularly in at least one plane perpendicular to the propagation of the light beam. The beam profile may be the transverse intensity profile of a light beam. The beam profile may be a cross-section of a light beam. The beam profile may be selected from the group consisting of a trapezoidal beam profile; a triangular beam profile; a linear combination of a conical beam profile and a Gaussian beam profile. However, other embodiments are possible. The projector may comprise at least one transfer device that may be configured to adjust, define, and/or determine the beam profile, in particular the shape of the beam profile.

The illumination features are spatially modulated. As used herein, the term "spatially modulated" may refer to a particular spatial arrangement and additional spatial arrangement of illumination features or portions of illumination features compared to a known regular pattern. The illumination pattern, and in particular the spatial arrangement of the illumination features, may be designed with respect to the field of view of the sensor element. Specifically, the illumination features may be patterned illumination features, each of which includes multiple subfeatures, and/or the illumination features may be arranged in a periodic pattern equidistant in rows, each of which has an offset, with the offsets of adjacent rows being different.

The illumination features are patterned illumination features. Each patterned illumination feature includes multiple subfeatures. As used herein, the term "patterned illumination feature" may refer to an illumination feature that includes multiple elements, called subfeatures. Subfeatures belonging to the same illumination feature may have the same shape. For example, an illumination feature may include multiple circles, each with a center and a radius. Subfeatures belonging to the same illumination feature may be located at different spatial locations in the illumination pattern. Specifically, the centers of the subfeatures are located at different spatial locations in the illumination pattern. The extension range of the subfeatures may be selected so that they are clearly distinguishable. For example, a patterned illumination feature may be or include a patterned light spot that includes multiple smaller light spots, or a cluster of several smaller light spots that are closely spaced to form a specific pattern. As used herein, "light spot" generally refers to a visible or detectable circular or non-circular illumination of an object by a light beam. Rotated versions of these patterned illumination features, such as those rotated 45 degrees, 90 degrees, or 180 degrees, may also be used. The selected patterned illumination feature can be replicated, for example, 1000-2000 times, to form the illumination pattern. In other words, the projected illumination pattern can include, for example, 1000-2000 copies of the selected patterned illumination feature.

For example, the projector may include a single light source, in particular a single laser light source, configured to generate at least one light beam, also referred to as a laser beam. The projector may include at least one transfer device for diffracting and replicating the laser beam generated by the single laser source, which generates an illumination pattern including patterned illumination features. In particular, the projector includes at least one diffractive optical element for diffracting and replicating the light beam. The diffractive optical element may be configured for beam shaping and/or beam splitting. As used herein, the term "replicate" may refer to generating multiple light beams from one light beam, in particular multiplying a light beam.

Additionally or alternatively, for example, the projector may include at least one array of densely packed light sources, particularly laser light sources, configured to generate a cluster of light beams according to a particular pattern. As used herein, the term "densely packed" light source may refer to multiple light sources arranged in a cluster. The density of the light sources may depend on the extension range of the housings of the individual light sources and the distinguishability of the light beams. The projector may include at least one redirection device for diffracting and replicating the cluster of light beams to generate an illumination pattern including patterned illumination features.

Additionally or alternatively, the illumination features are arranged in a periodic pattern equidistant in rows. Each row of illumination features has an offset, with the offset of adjacent rows being different. As used herein, the term "offset" may refer to the spatial distance between adjacent rows. The sensor elements and projector may be positioned so that the rows are parallel to the epipolar line. The illumination pattern may be selected so that two adjacent illumination features have an appropriate distance on the epipolar line. The distance between two illumination features may be such that the depth from photon ratio technique allows unambiguous assignment of two points on the epipolar line. The appropriate distance may depend on the distance error of the depth from photon ratio technique and/or the distance error of the sensor elements and projector from the baseline.

The illumination features may be arranged as follows: The illumination pattern may include multiple rows where the illumination features are equidistantly spaced at a distance d. The rows are orthogonal to the epipolar line. The distance between the rows may be constant. Different offsets may be applied to different rows in the same direction. The offsets may result in the illumination features of the rows being shifted. The offset δ is
where a and b are positive integers such that the illumination pattern is a periodic pattern. For example, δ can be 1/3 or 2/5. The offset and density of the illumination features can increase the robustness for solving the correspondence problem.

As used herein, the term "sensor element" generally refers to a device or a combination of devices configured to sense at least one parameter. In this case, the parameter may specifically be an optical parameter, and the sensor element may specifically be an optical sensor element. The sensor element may be formed as a single, integrated device or as a combination of several devices. As further used herein, the term "matrix" generally refers to an arrangement of multiple elements in a predetermined geometric order. As outlined in more detail below, the matrix may specifically be or include a rectangular matrix having one or more rows and one or more columns. The rows and columns may specifically be arranged in a rectangular fashion. However, it is noted that other arrangements, such as non-rectangular arrangements, are also possible. As an example, a circular arrangement is also possible, in which the elements are arranged in concentric circles or ellipses around a central point. For example, the matrix may be a single row of pixels. Other arrangements are also possible.

The optical sensors of the matrix may be identical in one or more of size, sensitivity, and other optical, electrical, and mechanical properties. The light-sensitive areas of all the optical sensors of the matrix may be arranged in a common plane, which may preferably face the object such that a light beam propagating from the object to the detector generates a light spot on the common plane.

As used herein, "photosensor" generally refers to a photosensitive device for detecting a light beam, e.g., for detecting illumination and/or light spots generated by at least one light beam. As used herein, "photosensitive area" generally refers to an area of a photo sensor that is externally illuminated by at least one light beam and generates at least one sensor signal in response to the illumination. The photosensitive area may specifically be located on the surface of each photo sensor. However, other embodiments are possible. As used herein, the term "photosensor having at least one photosensitive area" refers to both configurations including multiple single photo sensors, each having a photosensitive area, and configurations including a single combined photo sensor having multiple photosensitive areas. Thus, although the term "photosensor" also refers to a photosensitive device configured to generate one output signal, photosensitive devices configured to generate two or more output signals, e.g., at least one CCD and/or CMOS device, are referred to herein as two or more photo sensors. As outlined in more detail below, each photosensor may be embodied such that exactly one photosensitive area is present within each photosensor, for example by providing exactly one photosensitive area that can be illuminated, generating exactly one uniform sensor signal for the entire photosensor in response to illumination of the photosensitive area. Thus, each photosensor may be a single-area photosensor. The use of a single-area photosensor, however, makes the construction of the detector particularly simple and efficient. Thus, by way of example, commercially available photosensors, such as commercially available silicon photodiodes, each having exactly one photosensitive area, may be used in the construction. However, other embodiments are possible. Thus, by way of example, an optical device may be used that includes two, three, four, or more photosensitive areas, which would be considered two, three, four, or more photosensors in the context of the present invention. As outlined above, a sensor element comprises a matrix of photosensors. Thus, by way of example, a photosensor may be part of or constitute a pixelated optical device. By way of example, the photosensor may be part of or constitute at least one CCD and/or CMOS device having a matrix of pixels, each pixel forming a light-sensitive area.

As outlined above, the optical sensors may specifically be or include photodetectors, preferably inorganic photodetectors, more preferably inorganic semiconductor photodetectors, and most preferably silicon photodetectors. Specifically, the optical sensors may have sensitivity in the infrared spectral range. All of the optical sensors of the matrix, or at least one group of the optical sensors of the matrix, may specifically be identical. Groups of identical optical sensors of the matrix may specifically be provided for different spectral ranges, or all the optical sensors may be identical in terms of spectral sensitivity. Furthermore, the optical sensors may be identical in terms of size and/or their electronic or optoelectronic properties.

Specifically, the optical sensor may be or may include an inorganic photodiode having sensitivity in the infrared spectral range, preferably in the range of 780 nm to 3.0 micrometers. Specifically, the optical sensor may be sensitive in the near-infrared region, particularly in the range of 700 nm to 1000 nm, where silicon photodiodes are applicable. Infrared light sensors that can be used for the optical sensor may be commercially available infrared light sensors, such as those sold under the brand name Hertzstück® by trinamiX GmbH of D-67056 Ludwigshafen am Rhein, Germany. Thus, by way of example, the optical sensor may include at least one optical sensor of an intrinsic photovoltaic type, more preferably at least one semiconductor photodiode selected from the group consisting of a Ge photodiode, an InGaAs photodiode, an extended InGaAs photodiode, an InAs photodiode, an InSb photodiode, and an HgCdTe photodiode. Additionally or alternatively, the optical sensor may include at least one optical sensor of an extrinsic photovoltaic type, more preferably at least one semiconductor photodiode selected from the group consisting of a Ge:Au photodiode, a Ge:Hg photodiode, a Ge:Cu photodiode, a Ge:Zn photodiode, a Si:Ga photodiode, and an Si:As photodiode. Additionally or alternatively, the optical sensor may include at least one bolometer, preferably a bolometer selected from the group consisting of a VO bolometer and an amorphous Si bolometer.

The matrix may consist of independent light sensors. Thus, the matrix may consist of inorganic photodiodes. However, alternatively, one or more commercially available matrices may be used, for example, CCD detectors, such as CCD detector chips, and/or CMOS detectors, such as CMOS detector chips.

Thus, in general, the light sensors of the detector may form a sensor array or may be part of a sensor array such as the matrix described above. Thus, by way of example, the detector may have a light sensor array, such as a rectangular array having m rows and n columns, where m and n are independently positive integers. Preferably, there are more than one column and more than one row, i.e., n>1, m>1. Thus, by way of example, n may be 2 to 16 or more, and m may be 2 to 16 or more. Preferably, the ratio of the number of rows to the number of columns is close to 1. By way of example, n and m may be selected such that 0.3≦m/n≦3, such as by selecting m/n=1:1, 4:3, 16:9, or the like. By way of example, the array may be a square array having equal numbers of rows and columns, such as by selecting m=2, n=2, or m=3, n=3, etc.

The matrix may be specifically a rectangular matrix having at least one row, preferably multiple rows and multiple columns. By way of example, the rows and columns may be oriented substantially perpendicularly, and the definition above can be referenced for the term "substantially perpendicular." Thus, by way of example, a tolerance of less than 20°, specifically less than 10°, or even less than 5° may be tolerated. To provide a wide field of view, the matrix may specifically have at least 10 rows, preferably at least 50 rows, and more preferably at least 100 rows. Similarly, the matrix may have at least 10 columns, preferably at least 50 columns, and more preferably at least 100 columns. The matrix may include at least 50 photosensors, preferably at least 100 photosensors, and more preferably at least 500 photosensors. The matrix may include a number of pixels in the range of several megapixels. However, other embodiments are also possible. Therefore, in configurations where axial rotational symmetry is expected, a circular or concentric matrix of photosensors, also referred to as pixels, may be preferred.

Preferably, the sensor element may be oriented substantially perpendicular to the optical axis of the detector. Again, with regard to the term "substantially perpendicular," reference may be made to the definition and tolerances set forth above. The optical axis may be a straight optical axis, or may even be refracted or split, such as by using one or more deflection elements and/or by using one or more beam splitters; in the latter case, the substantially perpendicular orientation may refer to the local optical axis of each branch or beam path of the optical configuration.

The reflected light beam may propagate from the object towards the detector. The projector illuminates the object with an illumination pattern, and the light is reflected or scattered by the object and thereby directed at least partially towards the detector as a reflected light beam.

The reflected light beam may, in particular, completely illuminate the sensor element with a width of the light beam that is larger than the matrix, so that the sensor element is completely located within the light beam. Conversely, preferably, the reflected light beam may generate a light spot that is smaller than the matrix over the entire matrix, so that the light spot is completely located within the matrix. This situation can be easily adjusted by those skilled in the art of optics by selecting one or more appropriate lenses or elements that have a focusing or defocusing effect on the light beam, such as by using an appropriate transfer device, as will be outlined in more detail below.

As further used herein, "sensor signal" generally refers to a signal generated by an optical sensor in response to illumination by a light beam. Specifically, the sensor signal may be or may include at least one electronic signal, such as at least one analog electronic signal and/or at least one digital electronic signal. More specifically, the sensor signal may be or may include at least one voltage signal and/or at least one current signal. Even more specifically, the sensor signal may include at least one photocurrent. Additionally, the raw sensor signal may be used, or a detector, optical sensor, or other element may be configured to process or preprocess the sensor signal, such as by filtering, thereby generating a secondary sensor signal that may also be used as the sensor signal.

Specifically, the photosensitive areas may be oriented toward the object. As used herein, the term "oriented toward the object" generally refers to a state in which the surface of each of the photosensitive areas is fully or partially visible from the object. Specifically, at least one interconnection line between at least one point on the object and at least one point on each of the photosensitive areas may form an angle with the surface element of the photosensitive area that is different from 0°, for example, an angle in the range of 20° to 90°, preferably an angle in the range of 80° to 90°, for example, 90°. Therefore, when the object is on or near the optical axis, the light beam propagating from the object toward the detector may be substantially parallel to the optical axis. As used herein, the term "substantially perpendicular" refers to a perpendicular state, for example, with a tolerance of ±20° or less, preferably ±10° or less, and more preferably ±5° or less. Similarly, the term "substantially parallel" refers to a parallel state, for example, with a tolerance of ±20° or less, preferably ±10° or less, and more preferably ±5° or less.

The optical sensor may be sensitive in one or more of the ultraviolet, visible, or infrared spectral ranges. Specifically, the optical sensor may be sensitive in the visible spectral range of 500 nm to 780 nm, most preferably 650 nm to 750 nm, or 690 nm to 700 nm. Specifically, the optical sensor may be sensitive in the near-infrared region. Specifically, the optical sensor may be sensitive in the portion of the near-infrared region, particularly the 700 nm to 1000 nm range, where silicon photodiodes are applicable. Specifically, the optical sensor may be sensitive in the infrared spectral range, specifically the 780 nm to 3.0 micrometer range. For example, the optical sensors may each independently be or include at least one element selected from the group consisting of a photodiode, a photocell, a photoconductor, a phototransistor, or any combination thereof. For example, the light sensor may be or include at least one element selected from the group consisting of a CCD sensor element, a CMOS sensor element, a photodiode, a photocell, a photoconductor, a phototransistor, or any combination thereof. Any other type of photosensitive element may also be used. As outlined in more detail below, the photosensitive element generally can be made entirely or partially of inorganic materials and/or can be made entirely or partially of organic materials. Most commonly, one or more photodiodes, such as commercially available photodiodes, e.g., inorganic semiconductor photodiodes, may be used, as outlined in more detail below.

As used herein, the term "reflected image" refers to an image determined by an optical sensor that includes at least one reflective feature. As used herein, the term "reflective feature" refers to a feature in an image plane that is produced by an object in response to illumination by at least one illumination feature, for example. A reflected image may include at least one reflective pattern that includes at least one reflective feature. As used herein, the term "determining at least one reflected image" refers to one or more of imaging, recording, and generating a reflected image.

The sensor element may be configured to determine at least one reflection pattern. As used herein, the term "reflection pattern" refers to a response pattern produced by the reflection or scattering of light on the surface of an object, particularly a response pattern produced by an object in response to illumination by an illumination pattern. The reflection pattern may include at least one feature corresponding to at least one feature of the illumination pattern. The reflection pattern may include at least one distorted pattern compared to the illumination pattern, the distortion depending on the distance of the object, such as the surface characteristics of the object. The evaluation device may be configured to select at least one feature of the reflection pattern and determine the longitudinal extent of the selected feature of the reflection pattern by evaluating a combined signal Q from the sensor signal, as described above and in more detail below.

As further used herein, the term "evaluation device" generally refers to any device configured to perform specified operations, preferably by using at least one data processing device, and more preferably by using at least one processor and/or at least one application-specific integrated circuit. Thus, by way of example, at least one evaluation device may include at least one data processing device having software code stored thereon that includes a number of computer commands. The evaluation device may provide one or more hardware elements for performing one or more of the specified operations and/or may provide one or more processors having software executing thereon for performing one or more of the specified operations.

The above-described operations, including determining at least one longitudinal coordinate of the object, are performed by at least one evaluation device. Thus, by way of example, one or more of the relationships outlined below may be implemented in software and/or hardware, for example by implementing one or more look-up tables. Thus, by way of example, the evaluation device may comprise one or more programmable devices, such as one or more computers, application-specific integrated circuits (ASICs), digital signal processors (DSPs), or field-programmable gate arrays (FPGAs), configured to perform the above-described evaluations to determine at least one longitudinal coordinate of the object. Additionally or alternatively, however, the evaluation device may also be embodied entirely or partially in hardware.

As used herein, the term "selecting at least one reflection feature" refers to one or more of identifying, determining, and selecting at least one reflection feature of the reflection image. The detector may be configured to determine a longitudinal coordinate of an object point for at least one reflection feature of the reflection image from the combined signal. Accordingly, the detector may be configured to pre-classify at least one reflection feature of the reflection image and/or provide a distance estimate for the reflection feature. Specifically, the detector may be configured to determine more accurate distance information for at least one object by using triangulation and/or structured light techniques, taking into account the pre-classification and/or distance estimate.

The evaluation device may be configured to perform at least one image analysis and/or image processing to identify reflective features. The image analysis and/or image processing may use at least one feature detection algorithm. The image analysis and/or image processing may include one or more of: filtering; selecting at least one region of interest; forming a difference image between an image generated by the sensor signal and at least one offset; inverting the sensor signal by inverting the image generated by the sensor signal; forming a difference image between images generated by the sensor signal at different times; background correction; decomposition into color channels; decomposition into hue; saturation; and luminance channels; frequency decomposition; singular value decomposition; applying a Canny edge detector; applying a Laplacian of Gaussian filters; applying a difference of Gaussian filters; applying a Sobel operator; applying a Laplace operator; applying a Scharr operator; applying a Prewitt operator; applying a Roberts operator; applying a Kirsch operator; applying a high-pass filter; applying a low-pass filter; applying a Fourier transform; applying a Radon transform; applying a Hough transform; applying a wavelet transform; thresholding; and creating a binary image. The region of interest may be determined manually by a user or automatically, such as by recognizing an object in an image generated by an optical sensor.

The evaluation device is configured to determine at least one longitudinal coordinate z of a selected reflection feature of the reflection image by evaluating the combined signal Q from the sensor signals using a depth from photon ratio technique. The depth from photon ratio technique is generally known to those skilled in the art, such as from WO 2018/091649 A1, WO 2018/091638 A1, and WO 2018/091640 A1, the contents of which are incorporated by reference. The technique for determining distance by using photon ratios as described in WO 2018/091649 A1, WO 2018/091638 A1, and WO 2018/091640 A1 is referred to herein as "depth from photon ratio" or "beam profile analysis."

As used herein, the term "combined signal Q" refers to a signal generated by combining sensor signals, in particular by one or more of dividing the sensor signals, dividing a multiple of the sensor signals, or dividing a linear combination of the sensor signals. The evaluation device may be configured to derive the combined signal Q by one or more of dividing the sensor signals, dividing a multiple of the sensor signals, or dividing a linear combination of the sensor signals. The evaluation device may be configured to use at least one predetermined relationship between the combined signal Q and the longitudinal area to determine the longitudinal area. For example, the evaluation device is configured to derive the combined signal Q as follows:

where x and y are horizontal coordinates, A1 and A2 are different areas of at least one beam profile of the reflected light beam at the position of the sensor, and E(x, y, z _o ) represents the beam profile given by the object distance z _o . Area A1 and area A2 may be different. In particular, A1 and A2 are not congruent. Therefore, A1 and A2 may differ in one or more of shape or content.

In general, the beam profile depends on the brightness L(z _o ) and the beam shape S(x, y; z _o ), where E(x, y; z o ) = L·S. In this way, by deriving the combined signal, the longitudinal coordinate can be determined independently of the brightness. Furthermore, the combined signal can be used to determine the distance z _o independently of the size of the object. In this way, the combined signal makes it possible to determine the distance z o independently of the material properties and/or reflective and/or _scattering properties of the object and independently of changes in the light source due to, for example, manufacturing inaccuracies, heat, moisture, dirt, lens damage, etc.

Each of the sensor signals may include at least one piece of information for at least one area of the beam profile of the light beam. As used herein, the term "area of the beam profile" generally refers to any region of the beam profile at the sensor location used to determine the combined signal Q. The light-sensitive areas may be arranged such that a first sensor signal includes information for a first area of the beam profile, and a second sensor signal includes information for a second area of the beam profile. The first area of the beam profile and the second area of the beam profile may be adjacent or overlapping areas, or both. The first area of the beam profile and the second area of the beam profile may not exactly match in area.

The evaluation device may be configured to determine and/or select a first area of the beam profile and a second area of the beam profile. The first area of the beam profile may include substantially edge information of the beam profile, and the second area of the beam profile may include substantially central information of the beam profile. The beam profile may have a center, i.e., a maximum value of the beam profile and/or a central point of the plateau of the beam profile and/or a geometric center of the light spot, and a trailing edge extending from the center. The second area may include an inner area of the cross-section, and the first area may include an outer area of the cross-section. As used herein, the term "substantially central information" generally refers to a low percentage of edge information, i.e., a low percentage of the intensity distribution corresponding to the edge, compared to the percentage of central information, i.e., the percentage of the intensity distribution corresponding to the center. Preferably, the central information has an edge information percentage of less than 10%, more preferably less than 5%, and most preferably, the central information does not include edge content. As used herein, the term "substantially edge information" generally refers to a low percentage of central information compared to the percentage of edge information. The edge information may include information from the entire beam profile, particularly the central and edge regions. The edge information has a percentage of central information of less than 10%, preferably less than 5%, and more preferably the edge information does not include central information. If the beam profile is near or around the center and substantially includes central information, at least one area of the beam profile may be determined and/or selected as the second area of the beam profile. If the beam profile includes at least a portion of the falling edge of the cross section, at least one area of the beam profile may be determined and/or selected as the first area of the beam profile. For example, the entire area of the cross section may be determined as the first region. The first area of the beam profile may be area A2, and the second area of the beam profile may be area A1.

Other selections for the first area A1 and the second area A2 may be possible. For example, the first area may substantially include the outer region of the beam profile, and the second area may substantially include the inner region of the beam profile. For example, in the case of a two-dimensional beam profile, the beam profile may be divided into a left portion and a right portion, and the first area may substantially include the area of the left portion of the beam profile, and the second area may substantially include the area of the right portion of the beam profile.

The edge information may include information about the number of photons in a first area of the beam profile, and the center information may include information about the number of photons in a second area of the beam profile. The evaluation device may be configured to determine a surface integral of the beam profile. The evaluation device may be configured to determine the edge information by integration and/or summation of the first area. The evaluation device may be configured to determine the center information by integration and/or summation of the second area. For example, the beam profile may be a trapezoidal beam profile, and the evaluation device may be configured to determine the integral value of the trapezoid. Furthermore, when a trapezoidal beam profile is assumed, the determination of the edge and center signals may be replaced by an equivalent evaluation that utilizes characteristics of the trapezoidal beam profile, such as the slope and position of the edges and the height of the central plateau, and derives the edge and center signals through geometric considerations.

Additionally or alternatively, the evaluation device may be configured to determine center or edge information, or both, from at least one slice or cut of the light spot. This can be achieved, for example, by replacing the surface integral of the combined signal Q with a line integral along the slice or cut. To improve accuracy, several slices or cuts through the light spot can be used for averaging. In the case of an elliptical spot profile, averaging several slices or cuts may improve the distance information.

In one embodiment, a light beam propagating from an object to a detector can illuminate the sensor element with at least one pattern including at least one feature point. As used herein, the term "feature point" refers to at least one feature that is at least partially extended in the pattern. The feature point can be selected from the group consisting of at least one point, at least one line, and at least one edge. The pattern can be generated by the object in response to illumination by at least one light source having an illumination pattern including at least one pattern, for example. A1 can correspond to the total area or complete area of the feature point on the light sensor. A2 can be the central area of the feature point on the light sensor. The central area can be a constant value. The central area can be small compared to the total area of the feature point. For example, for a circular feature point, the central area can have a radius of 0.1 to 0.9 of the total radius of the feature point, preferably 0.4 to 0.6 of the total radius.

The evaluation device may be configured to derive the combined signal Q by one or more of the following: dividing the edge information by the center information; dividing a multiple of the edge information by the center information; or dividing a linear combination of the edge information by the center information. In this way, the photon ratio can essentially be used as the physical basis of the method.

For example, the evaluation device
a) determining at least one optical sensor having a highest sensor signal and forming at least one center signal;
b) evaluating the sensor signals of the optical sensors of the matrix and forming at least one sum signal;
c) determining at least one combined signal by combining the center signal and the sum signal; and d) determining at least one vertical coordinate z of the selected feature by evaluating the combined signal.
The sensor signal may be evaluated by

As described, for example, in WO 2012/110924 A1 or WO 2014/097181 A1, there is typically a predetermined or determinable relationship between the size of the light spot, such as the diameter, beam waist, or equivalent diameter, and the longitudinal coordinate of the object through which the light beam propagates toward the detector. Without wishing to be bound by this theory, a light spot can be characterized by two measurement variables: a measurement signal, also called the central signal, measured at the center of the light spot or a small measurement patch close to the center, and an integral or sum signal integrated over the light spot regardless of the presence or absence of the central signal. For a light beam with a specific total power that does not change when the beam expands or focuses, the sum signal should be independent of the spot size of the light spot and, therefore, independent of the distance between the object and the detector, at least when linear optical sensors are used within the respective measurement ranges. However, the central signal depends on the spot size. Therefore, the central signal typically increases when the light beam is focused and decreases when the light beam is defocused. Thus, by comparing the center signal and the sum signal, an item of information can be generated about the size of the light spot generated by the light beam, and therefore about the longitudinal coordinate of the object. The comparison of the center signal and the sum signal can be performed, for example, by forming a combined signal Q from the center signal and the sum signal, and by using a predetermined or determinable relationship between the longitudinal coordinate and the quotient signal to derive the longitudinal coordinate.

The use of a matrix of optical sensors offers several advantages and benefits. Thus, the center of the light spot generated by the light beam on a sensor element, such as the common plane of the light-sensitive areas of the optical sensors of the matrix of sensor elements, can vary depending on the lateral position of the object. By using a matrix of optical sensors, a detector according to the invention can adapt to these changing conditions and thus determine the center of the light spot simply by comparing the sensor signals. As a result, the detector according to the invention can itself select the center signal, determine the sum signal, and derive from these two signals a combined signal containing information about the longitudinal coordinate of the object. By evaluating the combined signal, the longitudinal coordinate of the object can thus be determined. The use of a matrix of optical sensors therefore offers considerable flexibility with regard to the position of the object, in particular the lateral position of the object.

The lateral position of the light spot on the matrix of light sensors, such as the lateral position of at least one light sensor generating a sensor signal, may be used as an additional item of information from which at least one item of information regarding the lateral position of the object is derived, as disclosed, for example, in WO 2014/198629 A1. Additionally or alternatively, as outlined in more detail below, a detector according to the invention may include at least one additional lateral detector for detecting at least one lateral coordinate of the object in addition to at least one longitudinal coordinate.

Therefore, according to the present invention, the term "central signal" generally refers to at least one sensor signal containing substantially central information of the beam profile. For example, the central signal may be the signal of at least one optical sensor having the highest sensor signal among multiple sensor signals generated by optical sensors in the entire matrix or in a region of interest within the matrix, which region of interest may be predetermined or determinable within the image generated by the optical sensors of the matrix. As used herein, the term "highest sensor signal" refers to one or both of a local maximum or maximum value in the region of interest. The central signal may originate from a single optical sensor, or, as outlined in more detail below, from a group of optical sensors. In the latter case, by way of example, the sensor signals of the group of optical sensors may be summed, integrated, or averaged to determine the central signal. The group of optical sensors from which the central signal originates may be a group of adjacent optical sensors, such as optical sensors located less than a predetermined distance from the actual optical sensor with the highest sensor signal, or may be a group of optical sensors that generate sensor signals within a predetermined range from the highest sensor signal. The group of optical sensors from which the central signal originates may be selected to be as large as possible to allow for the largest dynamic range. The evaluation device may be configured to determine the center signal by integrating multiple sensor signals, for example, sensor signals of multiple optical sensors around the optical sensor with the highest sensor signal. For example, the beam profile may be a trapezoidal beam profile, and the evaluation device may be configured to determine the integral of the trapezoid, in particular the plateau of the trapezoid.

As outlined above, the center signal may generally be a single sensor signal, such as a sensor signal from an optical sensor at the center of the light spot, or may be a combination of multiple sensor signals, such as a combination of sensor signals arising from optical sensors at the center of the light spot, or may be a secondary sensor signal derived by processing sensor signals derived from one or more of the foregoing possibilities. Determination of the center signal may be performed electronically, as comparison of sensor signals is fairly easily performed by conventional electronics, or may be performed fully or partially by software. Specifically, the center signal may be selected from the group consisting of: the highest sensor signal; the average of a group of sensor signals that are within a predetermined tolerance of the highest sensor signal; the average of sensor signals from a group of optical sensors including the optical sensor with the highest sensor signal and a predetermined group of adjacent optical sensors; the sum of sensor signals from a group of optical sensors including the optical sensor with the highest sensor signal and a predetermined group of adjacent optical sensors; the sum of a group of sensor signals that are within a predetermined tolerance of the highest sensor signal; the average of a group of sensor signals that exceed a predetermined threshold; the sum of a group of sensor signals that exceed a predetermined threshold; the integral of sensor signals from a group of optical sensors with the highest sensor signal and a predetermined group of adjacent optical sensors; the integral of a group of sensor signals that are within a predetermined tolerance of the highest sensor signal; or the integral of a group of sensor signals that exceed a predetermined threshold.

Similarly, the term "sum signal" generally refers to a signal that contains substantially edge information of the beam profile. For example, the sum signal can be derived by adding sensor signals, integrating sensor signals, or averaging sensor signals over the entire matrix or over a region of interest within the matrix, which region of interest may be predetermined or determinable within the image generated by the optical sensors of the matrix. When adding, integrating, or averaging sensor signals, the actual optical sensors from which the sensor signals are generated may be excluded from or included in the summation, integration, or averaging. The evaluation device may be configured to determine the sum signal by integrating signals over the entire matrix or over a region of interest within the matrix. For example, the beam profile may be a trapezoidal beam profile, and the evaluation device may be configured to determine the integral over the trapezoid. Furthermore, when a trapezoidal beam profile is assumed, determining the edge and center signals can be replaced by an equivalent evaluation that utilizes characteristics of the trapezoidal beam profile, such as determining the slope and position of the edges and the height of the central plateau, and derives the edge and center signals through geometric considerations.

Similarly, the center signal and edge signal can also be determined by using segments of the beam profile, such as a circular segment of the beam profile. For example, the beam profile can be divided into two segments by a secant or chord that does not pass through the center of the beam profile. Thus, one segment contains substantially edge information and the other segment contains substantially center information. For example, the edge signal can be further subtracted from the center signal to further reduce the amount of edge information in the center signal.

Additionally or alternatively, the evaluation device may be configured to determine center or edge information, or both, from at least one slice or cut of the light spot. This can be achieved, for example, by replacing the surface integral of the combined signal Q with a line integral along the slice or cut. To improve accuracy, several slices or cuts through the light spot can be used for averaging. In the case of an elliptical spot profile, averaging several slices or cuts may improve the distance information.

The combined signal may be a signal generated by combining the center signal and the sum signal. Specifically, the combining may include one or more of: forming a quotient of the center signal and the sum signal, or forming the inverse quotient; forming a quotient of a multiple of the center signal and a multiple of the sum signal, or forming the inverse quotient; forming a quotient of a linear combination of the center signals and a linear combination of the sum signal, or forming the inverse quotient. Additionally or alternatively, the combined signal may include any signal or combination of signals that includes at least one item of information regarding the comparison between the center signal and the sum signal.

The evaluation device may be configured to determine at least one longitudinal coordinate z of the object using at least one known, determinable, or predetermined relationship between the sensor signals. In particular, the evaluation device is configured to determine at least one coordinate z of the object using at least one known, determinable, or predetermined relationship between a quotient signal derived from the sensor signals and the longitudinal coordinate.

The raw sensor signals of the optical sensors may be used for evaluation or for deriving their secondary sensor signals. As used herein, the term "secondary sensor signal" generally refers to a signal, such as an electronic signal, more preferably an analog and/or digital signal, obtained by processing one or more raw signals, such as by filtering, averaging, or demodulation. Accordingly, image processing algorithms may be used to generate the secondary sensor signal from the entire matrix of sensor signals or from a region of interest within the matrix. Specifically, a detector, such as an evaluation device, may be configured to convert the sensor signals of the optical sensors, thereby generating the secondary optical sensor signal, and the evaluation device is configured to perform steps a) through d) using the secondary optical sensor signal. The transformation of the sensor signal may specifically include at least one transformation selected from the group consisting of: filtering; selecting at least one region of interest; forming a difference image between an image generated by the sensor signal and at least one offset; inverting the sensor signal by inverting the image generated by the sensor signal; forming a difference image between images generated by the sensor signal at different times; background correction; decomposition into color channels; decomposition into hue; saturation; and luminance channel; frequency decomposition; singular value decomposition; applying a Canny edge detector; applying a Laplacian of Gaussian filters; applying a difference of Gaussian filters; applying a Sobel operator; applying a Laplace operator; applying a Scharr operator; applying a Prewitt operator; applying a Roberts operator; applying a Kirsch operator; applying a high-pass filter; applying a low-pass filter; applying a Fourier transform; applying a Radon transform; applying a Hough transform; applying a wavelet transform; thresholding; and creating a binary image. The region of interest may be determined manually by a user or automatically, such as by recognizing an object in the image generated by the optical sensor. As an example, a vehicle, a person, or another type of predetermined object may be determined by automatic image recognition within the image, i.e., within the entire sensor signal generated by the optical sensor, and a region of interest may be selected such that the object is located within the region of interest. In this case, evaluations, such as determining the vertical coordinate, may be performed only on the region of interest. However, other implementations are possible.

As outlined above, the detection of the center of the light spot, i.e., the detection of the center signal and/or the at least one optical sensor from which the center signal originates, can be performed fully or partially electronically or fully or partially using one or more software algorithms. In particular, the evaluation device can comprise at least one center detector for detecting at least one highest sensor signal and/or for forming the center signal. The center detector can in particular be embodied fully or partially in software and/or fully or partially in hardware. The center detector can be fully or partially integrated into at least one sensor element and/or embodied fully or partially independent of the sensor element.

As outlined above, the sum signal can be derived from all sensor signals in the matrix excluding sensor signals from the photosensors contributing to the central signal, from sensor signals within the region of interest, or from one of these possibilities. In all cases, a reliable sum signal can be generated that can be reliably compared to the central signal to determine the vertical coordinate. In general, the sum signal can be selected from the group consisting of: an average of all sensor signals in the matrix; a sum of all sensor signals in the matrix; an integral of all sensor signals in the matrix; an average of all sensor signals in the matrix excluding sensor signals from the photosensors contributing to the central signal; a sum of all sensor signals in the matrix excluding sensor signals from the photosensors contributing to the central signal; an integral of all sensor signals in the matrix excluding sensor signals from the photosensors contributing to the central signal; a sum of sensor signals of photosensors within a predetermined range from the photosensor with the highest sensor signal; an integral of sensor signals of photosensors within a predetermined range from the photosensor with the highest sensor signal; a sum of sensor signals that exceed a predetermined threshold for photosensors located within a predetermined range from the photosensor with the highest sensor signal; or an integral of sensor signals that exceed a predetermined threshold for photosensors located within a predetermined range from the photosensor with the highest sensor signal. However, other options exist.

The summation may be performed fully or partially in software and/or fully or partially in hardware. The summation is possible by purely electronic means, which are usually easily implemented in detectors. Thus, in the field of electronics, summing devices are generally known which add two or more electronic signals, both analog and digital. The evaluation device may therefore comprise at least one summing device for forming a sum signal. The summing device may be fully or partially integrated into the sensor element or may be embodied fully or partially independent of the sensor element. The summing device may be embodied fully or partially in hardware and/or software.

As outlined above, the comparison between the center signal and the sum signal may be performed, in particular, by forming one or more quotient signals. Thus, in general, the combined signal may be a quotient signal Q derived by one or more of the following: forming a quotient of the center signal and the sum signal, or forming its inverse; forming a quotient of a multiple of the center signal and a multiple of the sum signal, or forming its inverse; forming a quotient of a linear combination of the center signals and a linear combination of the sum signal, or forming its inverse; forming a quotient of the center signal and a linear combination of the sum signal and the center signal, or forming its inverse; forming a quotient of the sum signal and a linear combination of the sum signal and the center signal, or forming its inverse; forming a quotient of a power of the center signal and a power of the sum signal, or forming its inverse. However, other options exist. The evaluation device may be configured to form one or more quotient signals. The evaluation device may further be configured to determine at least one vertical coordinate by evaluating at least one quotient signal.

The evaluation device may be specifically configured to use at least one predetermined relationship between the combined signal Q and the vertical coordinate to determine at least one vertical coordinate. Thus, for the reasons disclosed above and due to the dependence of the properties of the light spot on the vertical coordinate, the combined signal Q is typically a monotonic function of the vertical coordinate of the object and/or a monotonic function of the size of the light spot, such as the diameter or equivalent diameter of the light spot. Thus, by way of example, in the case where a linear light sensor is specifically used, the simple quotient Q = s _center / s _sum of the sensor signal s _center and the sum signal s _sum may be a monotonically decreasing function of distance. Without wishing to be bound by theory, this is believed to be due to the fact that, in the above-mentioned preferred configuration, both the center signal s _center and the sum signal s _sum decrease as a square function with increasing distance to the light source, since the amount of light reaching the detector decreases. However, in the optical configuration used in the experiment, the center signal s _center decreases more rapidly than the sum signal s _sum because the light spot in the image plane increases and thus spreads over a wider area. The quotient of the center signal and the sum signal therefore decreases continuously with the increase in the diameter of the light beam or light spot on the photosensitive area of the light sensor of the matrix. Furthermore, the quotient is usually independent of the total power of the light beam, since the total power of the light beam forms a coefficient of both the center signal and the sum sensor signal. As a result, the combined signal Q may form a quadratic signal that provides a unique and clear relationship between the center signal and the sum signal and between the size or diameter of the light beam. On the other hand, since the size or diameter of the light beam depends on the distance between the object through which the light beam propagates towards the detector and the detector itself, i.e., on the longitudinal coordinate of the object, a unique and clear relationship may exist between the center signal and the sum signal, on the one hand, and between the center signal and the longitudinal coordinate, on the other hand. Regarding the latter, reference may be made to one or more of the above-mentioned prior art documents, such as WO 2014/097181 A1, for example. The predetermined relationship can be determined by analytical considerations, for example by assuming a linear combination of Gaussian light beams, and/or by empirical measurements, such as measurements of the combined signal and/or the center signal and sum signal or secondary signals derived therefrom, as a function of the longitudinal coordinate of the object.

Thus, in general, the evaluation device can be configured to determine the vertical coordinate by evaluating the combined signal Q. This determination can be a one-step process, for example by directly combining the center signal and the sum signal to derive its vertical coordinate, or a multi-step process, for example by first deriving the combined signal from the center signal and the sum signal and secondly deriving the vertical coordinate from the combined signal. Both options are intended to be encompassed by the present invention, i.e., the option where steps c) and d) are separate and independent steps, and the option where steps c) and d) are fully or partially combined.

The evaluation device may be configured to use at least one predetermined relationship between the combined signal and the vertical coordinate. The predetermined relationship may be one or more of an empirical relationship, a semi-empirical relationship, and an analytically derived relationship. The evaluation device may include at least one data storage device for storing the predetermined relationship, such as a look-up list or a look-up table.

The combined signal Q may be determined using various means. By way of example, software means for deriving a quotient signal, hardware means for deriving a quotient signal, or both may be used and implemented in the evaluation device. Thus, by way of example, the evaluation device may include at least one divider, where the divider is configured to derive the quotient signal. The divider may be embodied, fully or partially, as a software divider or a hardware divider, or both. The divider may be embodied, fully or partially, as an integral part of the response of the sensor element, or may be embodied, fully or partially, independently of the sensor element.

Depth from photon ratio techniques enable reliable distance measurements with reduced computational demands, particularly reduced processing power, even in environments that cause multiple reflections from biased light sources or reflective measurement objects. The present invention enables identifying the material of a reflective object and estimating the distance of the reflective object to a projector or sensor element, even when there are various materials located at various distances from the sensor element, or when the projector produces nearly identical combinations of laser spot characteristics. Furthermore, the present invention enables estimating the orientation of a reflective surface and detecting edges. Illumination patterns that include spatially modulated illumination features can make at least one characteristic or parameter of the resulting modulated illumination feature more robust to variations caused by the physical properties of the material of the reflective target object. This at least one characteristic or parameter may depend only on the distance between the reflective object and the projector or sensor element. Other characteristics or parameters of the illumination feature can be modified and altered to provide information about the type and physical properties of the reflective material and its distance to the projector or sensor element. As outlined above, the illumination features may be patterned illumination features, each of which includes multiple sub-features. Illumination features that impinge on an object can illuminate the object. The object can generate corresponding reflection features in response to the impinging illumination features, for example, by reflection. The illumination features are patterned in this manner, and the reflection features are also patterned. The evaluation device may be configured to determine information regarding the distance between the object and the projector and/or sensor element by analyzing the patterned reflection features in the reflection image. The evaluation device may be configured to find and segment each patterned reflection feature. As used herein, the term "find" may refer to identifying a reflection feature in the reflection image that is generated in response to a corresponding illumination feature. Identification may include executing at least one object recognition algorithm to identify the feature in the reflection image. Identification may further include assigning the identified reflection feature to a corresponding illumination feature. As used herein, the term "segmentation" may refer to the process of dividing a reflection feature into multiple segments. A segment may correspond to a sub-feature in the reflection image that is generated in response to a corresponding sub-feature of the illumination feature. The evaluation device may be configured to determine the center of each of the sub-features. The evaluation device may be configured to determine the distance between the centers of the sub-features. The evaluation device may be configured to determine information about the distance between the object and the projector and/or sensor element from the distance between the centers of the sub-features using a predetermined relationship. The evaluation device may be configured to determine a corrected vertical coordinate z taking into account the determined distance between the object and the projector and/or sensor element. The corrected vertical coordinate may be a vertical coordinate with improved accuracy.

The evaluation device can be configured to identify the material properties of the object through speckle contrast estimation within each sub-feature. The evaluation device can be configured to determine a modified vertical coordinate z that takes the material properties into account. Specifically, laser spot profile analysis of the depth from defocus technique can be combined with estimation or calculation of speckle contrast within each laser spot to identify the material of a reflective object and more accurately estimate its distance to the projector or sensor element. Distance determination using the depth from photon ratio (DPR) technique described herein is a different technique for determining distance compared to depth from defocus. However, information determined by depth from photon ratio and depth from defocus can be combined for even more advanced distance determination.

The evaluation device may be configured for edge detection. The evaluation device may be configured to determine whether a patterned reflective feature is generated by an edge. The illumination feature may include at least three sub-features. When the illumination feature impinges on an object, it may generate a reflective feature including at least three sub-features corresponding to the sub-features of the illumination feature that generated the reflective feature. The evaluation device may be configured to determine whether a sub-feature of the reflective feature is generated by a flat reflective surface of the object or an edge of the object. The evaluation device may be configured to determine a longitudinal coordinate of the object for each sub-feature by evaluating a combined signal Q from the sensor signals of each sub-feature. The evaluation device may be configured to compare the longitudinal coordinates of the sub-features. If the longitudinal coordinates of the sub-features are identical within a tolerance range, the reflective surface that generated the sub-feature of the reflective feature may be considered flat. Otherwise, the object may be considered to be an edge or include an edge. The evaluation device may be configured to determine a normal and a local direction of the reflective surface of the object from the longitudinal coordinates determined from the sub-features. The evaluation device may be configured to determine a plane subtended by the subfeatures. The evaluation device may be configured to determine the surface normal of the plane and/or the orientation of the plane in space. For example, the orientation may be defined by the angle between the z-axis, in particular the optical axis, and the surface normal. Only one patterned illumination feature may be sufficient to allow the normal and local orientation of the reflecting surface to be estimated, and to allow knowing whether the patterned laser spot is reflected on an edge.

Furthermore, for problematic reflective surfaces, the probability of obtaining a usable laser spot reflection is higher when projecting such a dense cluster of spots compared to a relatively sparsely distributed single spot.

The present invention may enable improved performance of distance and depth measurements using depth-from-photon ratio techniques. This can be done through simple hardware modifications and simple computationally efficient additions to currently used algorithms. As a result, detectors can achieve better performance and be used for a number of additional applications.

The distances determined by DPR techniques provide distance estimates for each illumination feature and can be refined by triangulation using the known positions of the sensor element and projector. To calculate the refined vertical coordinates using triangulation, a so-called correspondence problem must be solved. When using a regular pattern, such as a rectangular pattern, two adjacent points may be directly adjacent on the epipolar line. For a robust correspondence problem, the physical distance between the features of the pattern may be large so that the point density of the pattern is low. As outlined above, the present application proposes that the illumination features be arranged in a periodic pattern with equidistant rows, where each row of illumination features has an offset, and the offsets of adjacent rows are different. The offsets enable reaching feature densities with large distances on the epipolar line, enhancing the robustness of the correspondence problem. The selection of the differential offset may be such that the structure of the illumination pattern can be designed with respect to the field of view of the sensor element.

The evaluation device may be configured to determine a longitudinal area of a selected reflection feature by evaluating the combined signal Q, the longitudinal area being given by a longitudinal coordinate z and an error interval ±ε. As used herein, the term "longitudinal area" refers to at least one uncertainty interval defined by the longitudinal coordinate z and the measurement uncertainty ±ε of the determination of the longitudinal coordinate from the combined signal Q. The error ε may depend on the measurement uncertainty of the optical sensor. The measurement uncertainty of the optical sensor may be determined and/or estimated in advance and/or stored in at least one data storage unit of the evaluation device. For example, the error interval may be ±10%, preferably ±5%, more preferably ±1%.

The evaluation device may be configured to determine at least one displacement region in the at least one reference image corresponding to the vertical region. As used herein, the term "reference image" refers to an image different from the reflected image, determined at a different spatial location compared to the reflected image. The reference image may be determined by one or more of recording at least one reference feature, imaging at least one reference feature, and calculating the reference image. The reference image and the reflected image may be images of an object determined at different spatial locations having a certain distance between them. The distance may be a relative distance, also referred to as a baseline. The evaluation device may be configured to determine at least one reference feature in the at least one reference image corresponding to the at least one reflected feature. As outlined above, the evaluation device may be configured to perform image analysis and identify features in the reflected image. The evaluation device may be configured to identify at least one reference feature in the reference image having substantially the same vertical coordinate as the selected reflected feature. The term "substantially identical" refers to identity within 10%, preferably within 5%, and most preferably within 1%. The reference feature corresponding to the reflected feature may be determined using epipolar geometry. For a description of epipolar geometry, see, for example, X. Jiang and H. Bunke, "Dreidimensionales Computersehen," Springer, Berlin Heidelberg, 1997. Epipolar geometry may assume that the reference image and the reflected image are images of an object determined at different spatial positions and/or spatial orientations having a fixed distance between them. The reference image and the reflected image may be images of an object determined at different spatial positions having a fixed distance between them. The evaluation device may be configured to determine an epipolar line in the reference image. The relative positions of the reference image and the reflected image may be known. For example, the relative positions of the reference image and the reflected image may be stored in at least one storage unit of the evaluation device. The evaluation device may be configured to determine a straight line extending from a selected reflection feature in the reflected image. The straight line may include a possible object feature corresponding to the selected feature. The straight line and the baseline develop an epipolar plane. Because the reference image is determined at a different relative position than the reflected image, corresponding possible object features can be imaged on lines called epipolar lines in the reference image. Therefore, features in the reference image that correspond to selected features in the reflected image lie on the epipolar lines. Due to image distortion or changes in system parameters due to aging, temperature changes, mechanical stress, etc., the epipolar lines may cross or be very close to each other, and/or the correspondence between the reference and reflected features may be unclear. Furthermore, each known location or object in the real world may be projected onto the reference image, or vice versa. While the projection can be known by detector calibration, calibration amounts to teaching-in the epipolar geometry of a particular camera.

As used herein, the term "displacement region" refers to a region in a reference image where a reference feature corresponding to a selected reflection feature may be imaged. Specifically, the displacement region can be a region in the reference image where a reference feature corresponding to a selected reflection feature is expected to be located in the reference image. Depending on the distance to the object, the image position of the reference feature corresponding to the reflection feature may be displaced in the reference image compared to the image position of the reflection feature in the reflection image. A displacement region may include only one reference feature. A displacement region may also include multiple reference features. A displacement region may include an epipolar line or a portion of an epipolar line. A displacement region may include multiple epipolar lines or multiple portions of multiple epipolar lines. As used herein, the term "reference feature" refers to at least one feature in a reference image. A displacement region may extend along an epipolar line, may extend perpendicular to the epipolar line, or both. The evaluation device may be configured to determine a reference feature along the epipolar line corresponding to a vertical coordinate z, and to determine a range of a displacement area along the epipolar line or orthogonal to the epipolar line corresponding to an error interval ±ε. Measurement uncertainty of distance measurement using the combined signal Q may result in a non-circular displacement area because the measurement uncertainty may vary with direction. Specifically, the measurement uncertainty along the epipolar line or multiple epipolar lines may be larger than the measurement uncertainty in an orthogonal direction relative to the epipolar line or multiple epipolar lines. The displacement area may include an area extending in an orthogonal direction relative to the epipolar line or multiple epipolar lines. The evaluation device may determine a displacement area around an image position of the reflection feature. The evaluation device may be configured to determine a vertical coordinate z of the reflection feature and an error interval ±ε from the combined signal Q to determine a displacement area along the epipolar line corresponding to z±ε. The evaluation device may be configured to match the selected reflection feature with at least one reference feature within the displacement area. As used herein, the term "matching" refers to determining and/or evaluating corresponding reference and reflection features. The evaluation device may be configured to match selected features of the reflection image with reference features within the displacement region by using at least one evaluation algorithm taking into account the determined vertical coordinate z. The evaluation algorithm may be a linear scaling algorithm. The evaluation device may be configured to determine an epipolar line closest to and/or within the displacement region. The evaluation device may be configured to determine an epipolar line closest to the image position of the reflection feature. The extent of the displacement region along the epipolar line may be greater than the extent of the displacement region perpendicular to the epipolar line. The evaluation device may be configured to determine the epipolar line before determining the corresponding reference feature. The evaluation device may determine a displacement region around the image position of each reflection feature. The evaluation device may be configured to assign an epipolar line to each displacement region at each image position of the reflection feature, such as by assigning an epipolar line closest to the displacement region and/or an epipolar line within the displacement region and/or an epipolar line closest to the displacement region along a direction orthogonal to the epipolar line. The evaluation device may be configured to determine a reference feature corresponding to the image position of the reflection feature by determining a reference feature closest to the assigned displacement region and/or a reference feature within the assigned displacement region and/or a reference feature closest to the assigned displacement region along the assigned epipolar line and/or a reference feature within the assigned displacement region along the assigned epipolar line.

Additionally or alternatively, the evaluation device may perform the following steps:
- determining the displacement area of the image location of each reflective feature;
- assigning an epipolar line to the displacement region of each reflection feature, such as by assigning the epipolar line closest to the displacement region and/or the epipolar line within the displacement region and/or the epipolar line closest to the displacement region along a direction perpendicular to the epipolar line;
- assigning and/or determining at least one reference feature to each reflection feature, such as by assigning a reference feature closest to the assigned displacement area and/or a reference feature within the assigned displacement area and/or a reference feature closest to the assigned displacement area along the assigned epipolar line and/or a reference feature within the assigned displacement area along the assigned epipolar line;
may be configured to perform

Additionally or alternatively, the evaluation device may be configured to determine between multiple epipolar lines and/or reference features to be assigned to a reflection feature, such as by comparing the distances of the reflection features and/or epipolar lines in the reference image and/or by comparing error-weighted distances, such as ε-weighted distances, of the reflection features and/or epipolar lines in the reference image and assigning the epipolar line and/or reference feature with the shorter distance and/or ε-weighted distance to the reference feature and/or reflection feature.

Preferably, the detector can be configured to pre-classify selected reflection features using the combined signal Q so that they can be unambiguously assigned to one reference feature. Specifically, the illumination features of the illumination pattern can be positioned such that corresponding reference features of the reference image have as large a relative distance as possible from each other on the epipolar line. The illumination features of the illumination pattern can be positioned such that only a small number of reference features are positioned on the epipolar line.

The evaluation device may be configured to determine the displacement of the matched reference feature and the selected reflection feature. As used herein, the term "displacement" refers to the difference between the position in the reference image and the position in the reflection image. The evaluation device may be configured to determine vertical information of the matched feature using a predetermined relationship between the vertical coordinate and the displacement. As used herein, the term "vertical information" refers to information about the vertical coordinate. For example, the vertical information may be a distance value. The evaluation device may be configured to determine the predetermined relationship by using triangulation. If the position of the selected reflection feature and the position of the matched reference feature in the reflection image and/or the relative displacement of the selected reflection feature and the matched reference feature are known, the vertical coordinate of the corresponding object feature may be determined by triangulation. Thus, the evaluation device may be configured to select reflection features, for example, sequentially and/or row by row, and to determine a corresponding distance value using triangulation for each potentially possible position of the reference feature. The displacement and the corresponding distance value may be stored in at least one storage device of the evaluation device. The evaluation device may include at least one data processing device, such as, by way of example, at least one processor, at least one DSP, at least one FPGA, and/or at least one ASIC. Furthermore, at least one data storage device may be provided to store at least one predetermined or determinable relationship between the vertical coordinate z and the displacement, such as by providing one or more look-up tables for storing the predetermined relationship. The evaluation device may be configured to store parameters for intrinsic and/or extrinsic calibration of the camera and/or detector. The evaluation device may be configured to generate parameters for intrinsic and/or extrinsic calibration of the camera and/or detector, such as by performing a Tsai camera calibration. The evaluation device may be configured to calculate and/or estimate parameters such as the focal length of the transfer device, the distortion coefficient of the radiation lens, the coordinate of the center of distortion of the radiation lens, a scale factor to account for uncertainties due to imperfections in the scanning and digitization hardware timing, the rotation angle of the transformation between world coordinates and camera coordinates, the translation component of the transformation between world coordinates and camera coordinates, the aperture angle, the image sensor type, the principal point, the skew factor, the camera center, the camera orientation, the baseline, the rotation or translation parameters of the camera and/or illumination source, the aperture, and the focal length.

Using the combined sensor signals allows for the estimation of distances, such as the vertical coordinate z within an error interval. By determining the displacement region corresponding to the estimated vertical coordinate and the corresponding error interval, the number of possible solutions along the epipolar line can be significantly reduced. The number of possible solutions can even be reduced to one. The determination of the vertical coordinate z and the error interval can be performed during pre-evaluation before matching the selected reflection feature with the reference feature. This can reduce computational requirements, thus significantly reducing costs and enabling use in mobile or outdoor devices. Furthermore, triangulation systems typically require a large baseline to detect large distances. Pre-evaluating the vertical coordinate z and the error interval using the combined sensor signals and then matching the selected reflection feature with the reference feature can allow for the use of a short baseline, thus providing a compact device. Furthermore, pre-evaluating the vertical coordinate z and the error interval using the combined sensor signals and then matching the selected reflection feature with the reference feature can improve accuracy and/or speed and/or reduce computational requirements compared to conventional triangulation systems. Additionally, the number of illumination features, such as the number of illumination points in an illumination pattern, can be reduced to increase the light intensity at each illumination point to compete with ambient light while complying with eye safety regulations. In conventional triangulation systems, reducing the number of illumination features can increase the difficulty of matching reflected features with reference features. Additionally, the number of illumination features, such as the number of illumination points in an illumination pattern, can be increased to increase the resolution of the resulting depth map without increasing the processing power of the evaluation device, such as in mobile applications, for example, to increase the resolution of distance measurements.

For example, the reference image may be an image of the illumination pattern at the image plane at the position of the projector. The evaluation device may be configured to determine a displacement region in the reference image that corresponds to a longitudinal region of a selected feature of the reflection pattern. The evaluation device may be configured to match the selected feature of the reflection pattern with at least one feature of the reference pattern within the displacement region. The projector and sensor element may be separated by a fixed distance.

For example, the detector may include at least two sensor elements, each having a matrix of optical sensors. At least one first sensor element and at least one second sensor element may be arranged at different spatial positions. The relative distance between the first and second sensor elements may be fixed. The at least one first sensor element may be configured to determine at least one first reflection pattern, particularly at least one first reflection feature, and the at least one second sensor element may be configured to determine at least one second reflection pattern, particularly at least one second reflection feature. The evaluation device may be configured to select at least one image determined by the first or second sensor element as a reflection image and select at least one image determined by the other of the first or second sensor element as a reference image. The evaluation device may be configured to select at least one reflection feature in the reflection pattern and determine a longitudinal area of the selected feature by evaluating a combined signal Q from the sensor signals. The evaluation device may be configured to determine a displacement area in the reference image corresponding to the longitudinal area of the selected feature of the reflection pattern. The evaluation device may be configured to match selected features of the reflected pattern with at least one feature of a reference pattern within the displacement region.

As outlined above, by evaluating the center signal and the sum signal, the detector may be able to determine at least one longitudinal coordinate of the object, including the option of determining the longitudinal coordinate of the entire object or one or more portions of the object. However, other coordinates of the object, including one or more lateral and/or rotational coordinates, may also be determined by the detector, particularly the evaluation device. Thus, by way of example, one or more lateral sensors may be used to determine at least one lateral coordinate of the object. As outlined above, the position of at least one optical sensor from which the center signal originates may provide information regarding at least one lateral coordinate of the object, where, by way of example, a simple lens equation may be used for the optical transformation and the derivation of the lateral coordinate. Additionally or alternatively, one or more additional lateral sensors may be used and included by the detector. Various lateral sensors, such as those disclosed in WO 2014/097181 A1 and/or other position sensing devices (PSDs), such as quadrant diodes, CCDs, or CMOS chips, are commonly known in the art. Additionally or alternatively, by way of example, a detector according to the present invention may include one or more PSDs as disclosed in R. A. Street (ed.): Technology and Applications of Amorphous Silicon, Springer-Verlag Heidelberg, 2010, pp. 346-349. Other embodiments are possible. These devices may generally be implemented in a detector according to the present invention. By way of example, a portion of a light beam may be split within the detector by at least one beam-splitting element. The split portion may be directed toward a lateral sensor, such as, by way of example, a CCD or CMOS chip or a camera sensor, and the lateral position of a light spot generated by the split portion on the lateral sensor may be determined, thereby determining at least one lateral coordinate of the object. Thus, a detector according to the present invention may be a one-dimensional detector, such as a simple distance measuring device, or may be embodied as a two-dimensional detector or even a three-dimensional detector. Also, a three-dimensional image may be generated by scanning a scene or environment one-dimensionally, as outlined above or in more detail below. Thus, the detector according to the present invention may in particular be one of a one-dimensional detector, a two-dimensional detector, or a three-dimensional detector. The evaluation device may further be configured to determine at least one lateral coordinate x, y of the object. The evaluation device may be configured to combine information on the lateral and longitudinal coordinates to determine the position of the object in space.

In a further aspect, the present invention discloses a method for determining the position of at least one object by using a detector such as a detector according to the present invention, e.g., according to one or more embodiments referenced above or as disclosed in more detail below. Nevertheless, other types of detectors may be used. The method includes the following method steps, where the method steps may be performed in a given order or in a different order. Furthermore, there may be one or more additional method steps not listed. Furthermore, one, more than one, or even all of the method steps may be performed repeatedly.

The method comprises the following method steps:
- illuminating the object with at least one illumination pattern generated by at least one projector of a detector, said illumination pattern comprising a plurality of illumination features, said illumination features being spatially modulated;
generating, in response to illumination, at least one sensor signal for each reflected light beam incident on a light-sensitive area of a light sensor of a sensor element comprising a matrix of said light sensors;
- determining at least one reflected image using said sensor elements;
- selecting at least one reflection feature of said reflection image and evaluating said sensor signals using at least one evaluation device, thereby determining at least one vertical coordinate z of said selected reflection feature, said evaluation comprising evaluating a combined signal Q from said sensor signals;
It has.

For details, options, and definitions, reference may be made to the detectors described above. Thus, in particular, as explained above, the method may include the use of a detector according to the present invention, such as according to one or more embodiments provided above or in more detail below.

In a further aspect of the present invention, the use of a detector according to the present invention, such as according to one or more of the embodiments given above or in more detail below, is proposed for use selected from the group consisting of: position measurement in traffic technology; entertainment applications; security applications; surveillance applications; safety applications; human-machine interface applications; tracking applications; photography applications; imaging or camera applications; mapping applications for generating at least one map of a space; homing or tracking beacon detectors for vehicles; outdoor applications; mobile applications; communication applications; machine vision applications; robotics applications; quality control applications; and manufacturing applications. For further uses of the detector and device of the present invention, reference is made to WO 2018/091649 A1, WO 2018/091638 A1 and WO 2018/091640 A1, the contents of which are incorporated by reference.

As used herein, the terms "have," "comprise," and "include," as well as their grammatical variations, are used in a non-exclusive manner. These terms can therefore refer both to a situation in which no further features are present in the subject matter described in this context, in addition to the features introduced by these terms, and to a situation in which one or more further features are present. For example, the terms "A has B," "A comprises B," and "A includes B" can refer both to a situation in which no other elements are present in A besides B (i.e., a situation in which A consists solely and exclusively of B), and to a situation in which, in addition to B, one or more further elements are present in entity A, such as element C, elements C and D, or even another element.

Furthermore, it should be noted that the terms "at least one," "one or more," or similar expressions indicating that a feature or element may be present one or more times will typically be used only once when introducing each feature or element. In most cases, when referring to each feature or element, the expressions "at least one" or "one or more" will not be repeated, regardless of the fact that each feature or element may be present one or more times.

Furthermore, as used below, the terms "preferably," "more preferably," "particularly," "more particularly," "particularly," "more particularly," or similar terms may be used in conjunction with any feature without limiting alternative possibilities. Therefore, features introduced by these terms are optional features and are not intended to limit the scope of the claims in any way. As those skilled in the art will recognize, the present invention may be practiced by using alternative features. Similarly, features introduced by "in an embodiment of the invention" or similar expressions do not impose any limitations on alternative embodiments of the invention, do not impose any limitations on the scope of the invention, and do not impose any limitations on the possibility of combining the feature so introduced with other optional or non-optional features of the invention.

Overall, in the context of the present invention, the following embodiments are considered preferred:

Embodiment 1: A detector for determining the position of at least one object, said detector comprising:
at least one projector for illuminating an object with at least one illumination pattern, said illumination pattern comprising a plurality of illumination features, said illumination features being spatially modulated; and
at least one sensor element having a matrix of light sensors, each having a light-sensitive area, each light sensor designed to generate at least one sensor signal in response to illumination of its respective light-sensitive area by a reflected light beam propagating from the object to the detector, said sensor element being configured to determine at least one reflected image;
at least one evaluation device, said evaluation device being configured to select at least one reflection feature of said reflection image, said evaluation device being configured to determine at least one longitudinal coordinate z of said selected reflection feature of said reflection image by using a depth from photon ratio technique by evaluating a combined signal Q from said sensor signals;
Including,
A detector, wherein the illumination features are patterned illumination features, each of the patterned illumination features including a plurality of sub-features, and/or the illumination features are arranged in a periodic pattern equidistant in rows, each of the rows of illumination features having an offset, and the offsets of adjacent columns are different.

Embodiment 2: A detector according to the preceding embodiment, wherein the projector comprises at least one light source configured to generate at least one light beam, and the projector comprises at least one redirector configured to diffract and replicate the light beam to generate the illumination pattern including patterned illumination features.

Embodiment 3: A detector according to any one of the preceding embodiments, wherein the projector comprises at least one array of light sources spaced according to a particular pattern and configured to generate clusters of light beams, and the projector comprises at least one redirector for diffracting and replicating the clusters of light beams to generate an illumination pattern including the patterned illumination features.

Embodiment 4: A detector according to any one of the preceding embodiments, wherein the evaluation device is configured to determine information regarding the distance between the object and the projector and/or the sensor element by analyzing patterned reflection features of the reflection image.

Embodiment 5: A detector according to the preceding embodiment, wherein the evaluation device is configured to locate and segment each patterned illumination feature, the evaluation device is configured to determine a center of each of the sub-features, the evaluation device is configured to determine a distance between the centers of the sub-features, and the evaluation device is configured to determine information regarding a distance between the object and the projector and/or the sensor element from the distance between the centers of the sub-features using a predetermined relationship.

Embodiment 6: A detector according to any one of the preceding two embodiments, wherein the evaluation device is configured to determine a corrected vertical coordinate z taking into account a determined distance between the object and the projector and/or the sensor element.

Embodiment 7: A detector according to any one of the preceding embodiments, wherein the evaluation device is configured to identify material properties of the object by speckle contrast estimation within each sub-feature, and the evaluation device is configured to determine a modified vertical coordinate z taking into account the material properties.

Embodiment 8: A detector according to any one of the preceding embodiments, wherein the evaluation device is configured for edge detection, the illumination feature includes at least three sub-features, the evaluation device is configured to determine a longitudinal coordinate of the object for each of the sub-features by evaluating a combined signal Q from the sensor signals of each sub-feature, and the evaluation device is configured to determine a normal and a local direction of a reflective surface of the object from the longitudinal coordinates determined from the sub-features.

Embodiment 9: A detector according to any one of the preceding embodiments, wherein the sensor elements and the projector are positioned such that the rows are parallel to an epipolar line.

Embodiment 10: The offset δ is
10. A detector according to any one of the preceding nine embodiments, wherein a and b are integers.

Embodiment 11: A detector according to any one of the preceding embodiments, wherein the evaluation device is configured to derive the combined signal Q by one or more of dividing the sensor signals, dividing a multiple of the sensor signals, or dividing a linear combination of the sensor signals, and the evaluation device is configured to use at least one predetermined relationship between the combined signal Q and the vertical coordinate z to determine the vertical coordinate.

Embodiment 12: A detector according to any one of the preceding embodiments, wherein the evaluation device is configured to determine a longitudinal area of the selected reflection feature by evaluating the combined signal Q, the longitudinal area being given by the longitudinal coordinate z and an error interval ±ε; the evaluation device is configured to determine at least one displacement area in at least one reference image corresponding to the longitudinal area; the evaluation device is configured to match the selected reflection feature with at least one reference feature within the displacement area; the evaluation device is configured to determine a displacement of the matched reference feature and the selected reflection feature; and the evaluation device is configured to determine longitudinal information of the matched feature using a predetermined relationship between the longitudinal coordinate and the displacement.

Embodiment 13: A method for determining the position of at least one object by using a detector according to any one of the preceding embodiments, said method comprising the following method steps:
- illuminating the object with at least one illumination pattern generated by at least one projector of a detector, wherein the illumination pattern comprises a plurality of illumination features, the illumination features being spatially modulated, the illumination features being patterned illumination features, each of the patterned illumination features comprising a plurality of sub-features, and/or the illumination features being arranged in a periodic pattern equidistant in rows, each of the rows of illumination features having an offset, the offsets of adjacent columns being different;
generating, in response to illumination, at least one sensor signal for each reflected light beam incident on a light-sensitive area of a light sensor of a sensor element comprising a matrix of said light sensors;
- determining at least one reflected image using said sensor elements;
- selecting at least one reflection feature of said reflection image and evaluating said sensor signals using at least one evaluation device, thereby determining at least one vertical coordinate z of said selected reflection feature, said evaluation comprising evaluating a combined signal Q from said sensor signals;
A method comprising:

Embodiment 14: Use of a detector according to any one of the preceding embodiments, wherein the purpose of use is selected from the group consisting of position measurement in traffic technology, entertainment applications, security applications, surveillance applications, safety applications, human-machine interface applications, logistics applications, tracking applications, outdoor applications, mobile applications, communications applications, photography applications, machine vision applications, robotics applications, quality control applications, and manufacturing applications.

Optional further details and features of the present invention will become apparent from the following description of preferred exemplary embodiments in conjunction with the dependent claims. In this context, certain features may be implemented individually or in combination with other features. The present invention is not limited to the exemplary embodiments, which are shown diagrammatically in the figures. Identical reference numerals in the individual figures refer to identical elements or elements with identical functions or which correspond to each other in terms of their functions.

Specifically, in the following diagram:
1 shows an embodiment of a detector according to the present invention; 2A and 2B are diagrams illustrating embodiments of illumination patterns. 3A and 3B are diagrams illustrating further embodiments of illumination features and illumination patterns.

1 shows, in a highly schematic manner, an embodiment of a detector 110 for determining the position of at least one object 112 according to the present invention. The detector 110 comprises at least one sensor element 114 having a matrix 116 of light sensors 118. Each of the light sensors 118 comprises a light-sensitive area 120.

The sensor elements 114 may be formed as a single, integral device or as a combination of several devices. The matrix 116 may specifically be or include a rectangular matrix having one or more rows and one or more columns. The rows and columns may specifically be arranged in a rectangular manner. However, other arrangements are possible, such as non-rectangular arrangements. As an example, a circular arrangement is also possible, in which the elements are arranged in concentric circles or ellipses around a central point. For example, the matrix 116 may be a single row of pixels. Other arrangements are also possible.

The optical sensors 118 of the matrix 116 may be identical in one or more of size, sensitivity, and other optical, electrical, and mechanical properties. The photosensitive areas 120 of all the optical sensors 118 of the matrix 116 may be arranged in a common plane, which may preferably face the object such that a light beam propagating from the object 112 to the detector 110 generates a light spot on the common plane. The photosensitive areas 120 may be located on the surface of each optical sensor 118. However, other embodiments are also possible.

The photosensors 118 may include, for example, at least one CCD and/or CMOS device. By way of example, the photosensors 118 may be part of or form part of a pixelated optical device. By way of example, the photosensors may be part of or form part of at least one CCD and/or CMOS device having a matrix of pixels, each pixel forming a light-sensitive area 120. Preferably, the detectors are configured such that the photosensors 118 are simultaneously exposed within a fixed period of time, called a frame or imaging frame. For example, the photosensors 118 may be part of or form part of at least one global shutter CMOS device.

The light sensors 118 may be or may include photodetectors, preferably inorganic photodetectors, more preferably inorganic semiconductor photodetectors, and most preferably silicon photodetectors. Specifically, the light sensors 118 may be sensitive in the infrared spectral range. All of the light sensors 118 in the matrix 116, or at least a group of the light sensors 118 in the matrix 116, may be identical. Groups of identical light sensors 118 in the matrix 116 may be provided for different spectral ranges, or all light sensors may be identical in terms of spectral sensitivity. Furthermore, the light sensors 118 may be identical in terms of size and/or their electronic or optoelectronic properties. The matrix 116 may be composed of individual light sensors 118. Thus, the matrix 116 may be composed of inorganic photodiodes. Alternatively, however, one or more commercially available matrices may be used, e.g., CCD detectors, such as CCD detector chips, and/or CMOS detectors, such as CMOS detector chips.

The light sensors 118 may form a sensor array or may be part of a sensor array, such as the matrix described above. Thus, by way of example, the detector 110 may have an array of light sensors 118, such as a rectangular array having m rows and n columns, where m and n are independently positive integers. Preferably, there are more than one column and more than one row, i.e., n>1, m>1. Thus, by way of example, n may be 2 to 16 or more, and m may be 2 to 16 or more. Preferably, the ratio of the number of rows to the number of columns is close to 1. By way of example, n and m may be selected such that 0.3≦m/n≦3, such as by selecting m/n=1:1, 4:3, 16:9, or the like. By way of example, the array may be a square array having equal numbers of rows and columns, such as by selecting m=2, n=2, or m=3, n=3, etc.

The matrix 116 may be specifically a rectangular matrix having at least one row, preferably multiple rows and multiple columns. By way of example, the rows and columns may be oriented in a substantially perpendicular direction. To provide a wide field of view, the matrix 116 may specifically have at least 10 rows, preferably at least 50 rows, and more preferably at least 100 rows. Similarly, the matrix may have at least 10 columns, preferably at least 50 columns, and more preferably at least 100 columns. The matrix 116 may include at least 50 photosensors 118, preferably at least 100 photosensors 118, and more preferably at least 500 photosensors 118. The matrix 116 may include a number of pixels in the range of several megapixels. However, other embodiments are also possible.

The detector 110 further includes a projector 122 for illuminating the object 112 with at least one illumination pattern 124. The projector 122 may include at least one laser source 126, in particular for generating at least one light beam. The projector 122 may include at least one diffractive optical element 128, in particular for generating and/or forming the illumination pattern 124 from the light beam of the laser source 126. The projector 122 may be configured such that the illumination pattern 124 propagates from the projector 122, in particular from at least one opening 130 in a housing of the projector 122, toward the object 112. The projector 122 may be configured to generate and/or project a point cloud; for example, the projector 122 may include at least one digital light processing (DLP) projector, at least one LCoS projector, at least one laser source, at least one array of laser sources; at least one light emitting diode; or at least one array of light emitting diodes. The laser light source 126 may include focusing optics 134. The projector 122 may include multiple laser light sources 126. Additionally, additional illumination patterns may be generated by at least one ambient light source.

The projector 122 may include at least one control unit 136. The control unit 136 may be configured to control the laser source 126. The control unit 136 may include at least one processing device, particularly at least one processor and/or at least one application-specific integrated circuit (ASIC). The control unit 136 may comprise one or more programmable devices, such as one or more computers, application-specific integrated circuits (ASICs), digital signal processors (DSPs), or field-programmable gate arrays (FPGAs), configured to perform control of the laser source 126. The control unit 136 may include at least one processing device having software code stored thereon, including multiple computer commands. The control unit 136 may provide one or more hardware elements for performing control of the laser source 126 and/or one or more processors having software running thereon to perform control of the laser source. The control unit 136 may be configured to issue and/or generate at least one electronic signal for performing control of the laser source. The control unit 136 may have one or more wireless and/or wired interfaces and/or other types of control connections for controlling the laser source 126. The control unit 136 and the laser source may be interconnected by one or more connectors and/or one or more interfaces.

The illumination pattern 124 includes a plurality of illumination features 125. The illumination pattern 124 may include at least one pattern selected from the group consisting of: at least one point pattern, particularly a pseudo-random point pattern; a random point pattern or a quasi-random pattern; at least one Sobol pattern; at least one quasi-periodic pattern; at least one pattern including at least one known feature; at least one regular pattern; at least one triangular pattern; at least one hexagonal pattern; at least one rectangular pattern; at least one pattern including convex uniform tiling; at least one line pattern including at least one line; or at least one line pattern including at least two lines, such as parallel or intersecting lines. For example, the projector 122 may be configured to generate and/or project a point cloud. For example, the projector 122 may be configured to generate a point cloud such that the illumination pattern may include a plurality of point features.

The illumination features 125 are spatially modulated. The illumination pattern, and in particular the spatial arrangement of the illumination features 125, may be designed with respect to the field of view of the sensor element 114. Specifically, the illumination features 125 are patterned illumination features 125, each of which includes multiple sub-features, and/or the illumination features 125 are arranged in a periodic pattern equidistant in rows, each of which has an offset, with the offsets of adjacent rows being different.

As shown in FIG. 2A , the illumination features 125 may be arranged in a periodic pattern, equidistant in rows. The distance between adjacent illumination features on a row may be d. Each row of illumination features 125 may have an offset δ, with the offsets for adjacent rows being different. The offset δ may be the spatial distance between adjacent rows. The sensor elements 114 and projector 122 in FIG. 1 may be positioned such that the rows are parallel to the epipolar line 137. The illumination pattern 124 may be selected such that two adjacent illumination features 125 have an appropriate distance on the epipolar line 124. The distance between the two illumination features 125 may be such that the depth from photon ratio technique can unambiguously assign two points on the epipolar line 124. The appropriate distance may depend on the distance error of the depth from photon ratio technique and/or the distance error of the sensor elements 114 and projector 122 from the baseline.

The illumination features 125 may be arranged as follows: The illumination pattern 124 may include multiple rows in which the illumination features 125 are equidistantly spaced at a distance d. The rows are orthogonal to the epipolar line 137. The distance between the rows may be constant. Different offsets may be applied to different rows in the same direction. The offsets may result in the illumination features of the rows being shifted. The offset δ is
where a and b are positive integers such that the illumination pattern is a periodic pattern. For example, δ can be 1/3 or 2/5. The illumination pattern 124 constructed in this way exhibits a shifted grid compared to the initial regular rectangular pattern. The distance between features on the epipolar lines 137 of this grid arrangement is three times larger than that of the initial regular rectangular pattern. The offset and density of the illumination features 125 can increase the robustness for solving the correspondence problem. FIG. 2B shows the illumination pattern 124 in the field of view 139 of the sensor element 114. By using the offset, the illumination features 125 can be positioned so that the illumination pattern 124 coincides with the field of view 139 of the sensor element 114.

The illumination features 125 may be patterned illumination features. Each patterned illumination feature may include multiple sub-features 141. The sub-features 141 belonging to the same illumination feature 125 may have the same shape. For example, the illumination feature 125 may include multiple circles, each having a center and a radius. The sub-features 141 belonging to the same illumination feature 125 may be located at different spatial positions in the illumination pattern 124. Specifically, the centers of the sub-features 141 are located at different spatial positions in the illumination pattern 124. The extension range of the sub-features 141 may be selected so that they are clearly distinguishable. For example, the patterned illumination feature 125 may be or include a patterned light spot that includes multiple smaller light spots, or a cluster of several smaller light spots that are closely spaced to form a particular pattern. Rotated versions of these patterned illumination features, such as those rotated 45 degrees, 90 degrees, or 180 degrees, may also be used. The selected patterned illumination feature 125 can be replicated, for example, 1000-2000 times, to form the illumination pattern 124. In other words, the projected illumination pattern 124 can include, for example, 1000-2000 copies of the selected patterned illumination feature 125.

For example, the projector 122 of FIG. 1 may include a single light source, specifically a single laser source 126, configured to generate at least one light beam, also denoted a laser beam. The projector 122 may include at least one transfer device, specifically a DOE 128, for diffracting and replicating the laser beam generated by the single laser source to generate an illumination pattern 124 including patterned illumination features. The diffractive optical element 128 may be configured for beam shaping and/or beam splitting.

For example, the projector 122 may include at least one array of closely spaced light sources, particularly laser light sources 126, configured to generate a cluster of light beams according to a particular pattern. The density of the laser light sources 126 may depend on the housing extension of the individual light sources and the distinguishability of the light beams. The projector 122 may include at least one redirection device, particularly a DOE 128, for diffracting and replicating the cluster of light beams to generate an illumination pattern 124 including patterned illumination features.

Figure 3A shows an example of patterned illumination features that can be used to form an illumination pattern 124 projected onto an object 112. The top row of illumination features 125 includes four sub-features 141 with different spatial arrangements. Shown from left to right in the bottom row are an illumination feature 125 with two sub-features 141, an illumination feature 125 with three sub-features 141, and an illumination feature 125 with seven sub-features 141. Figure 3B shows a projected illumination pattern 124 including 26 patterned illumination features 125 with sub-features 142.

1, each optical sensor 118 is designed to generate at least one sensor signal in response to illumination of its respective photosensitive area 120 by a reflected light beam propagating from the object 112 to the detector 110. Furthermore, the sensor elements 114 are configured to determine at least one reflection image 142 including at least one reflection pattern 138. The reflection image 142 may include points as reflection features. These points are caused by the reflected light beam emanating from the object 112. The sensor elements 114 may be configured to determine the reflection pattern 138. The reflection pattern 138 may include at least one feature corresponding to at least one illumination feature 125 of the illumination pattern 124. The reflection pattern 138 may include at least one distorted pattern compared to the illumination pattern 124, where the distortion depends on the distance of the object 112, such as the surface characteristics of the object 112.

The detector 110 may comprise at least one transfer device 140 including one or more of the following: at least one lens, for example at least one lens selected from the group consisting of at least one adjustable-focus lens, at least one aspherical lens, at least one spherical lens, and at least one Fresnel lens; at least one diffractive optical element; at least one concave mirror; at least one beam-deflecting element, preferably at least one mirror; at least one beam-splitting element, preferably at least one of a beam-splitting cube or a beam-splitting mirror; or at least one multi-lens system. In particular, the transfer device 140 may include at least one collimating lens configured to focus on at least one object point in the image plane.

The detector 110 includes at least one evaluation device 144. The evaluation device 144 is configured to select at least one reflection feature of the reflection image 142. The evaluation device 144 may be configured to select at least one feature of the reflection pattern 138 and determine the vertical coordinate of the selected feature of the reflection pattern by evaluating the combined signal Q from the sensor signals, as described above. Thus, the detector 110 may be configured to pre-classify at least one reflection feature of the reflection image 142.

The evaluation device 144 may be configured to perform at least one image analysis and/or image processing to identify reflective features. The image analysis and/or image processing may use at least one feature detection algorithm. The image analysis and/or image processing may include one or more of: filtering; selecting at least one region of interest; forming a difference image between an image generated by the sensor signal and at least one offset; inverting the sensor signal by inverting the image generated by the sensor signal; forming a difference image between images generated by the sensor signal at different times; background correction; decomposition into color channels; decomposition into hue; saturation; and luminance channels; frequency decomposition; singular value decomposition; applying a Canny edge detector; applying a Laplacian of Gaussian filters; applying a difference of Gaussian filters; applying a Sobel operator; applying a Laplace operator; applying a Scharr operator; applying a Prewitt operator; applying a Roberts operator; applying a Kirsch operator; applying a high-pass filter; applying a low-pass filter; applying a Fourier transform; applying a Radon transform; applying a Hough transform; applying a wavelet transform; thresholding; and creating a binary image. The region of interest may be determined manually by a user or automatically, such as by recognizing an object in the image generated by the optical sensor 118.

The evaluation unit 144 is configured to determine at least one vertical coordinate z of a selected reflection feature of the reflection image 142 by evaluating a combined signal Q from the sensor signals. The evaluation unit 144 may be configured to derive the combined signal Q by one or more of dividing the sensor signals, dividing a multiple of the sensor signals, or dividing a linear combination of the sensor signals. The evaluation unit 144 may be configured to use at least one predetermined relationship between the combined signal Q and the vertical area to determine the vertical area. For example, the evaluation unit 144 is configured to derive the combined signal Q as follows:

where x and y are horizontal coordinates, A1 and A2 are different areas of at least one beam profile of the reflected light beam at the sensor position, and E(x, y, z _o ) represents the beam profile given by the object distance z _o . Area A1 and area A2 may be different. In particular, A1 and A2 are not congruent. Thus, A1 and A2 may differ in one or more of shape or content. The beam profile may be the horizontal intensity profile of the light beam. The beam profile may be the cross-section of the light beam. The beam profile may be selected from the group consisting of a trapezoidal beam profile; a triangular beam profile; a conical beam profile; and a linear combination of a Gaussian beam profile. In general, the beam profile depends on the intensity L(z _o ) and the beam shape S(x, y; z _o ), where E(x, y; z _o ) = L·S. In this way, by deriving the combined signal, the vertical coordinate can be determined independently of the intensity. Furthermore, the combined signal can be used to determine the distance z ₀ independently of the size of the object. In this way, the combined signal allows the distance z 0 to be determined independently of the material and/or reflective and/or _scattering properties of the object and independently of variations in the light source due to, for example, manufacturing inaccuracies, heat, moisture, dirt, lens damage, etc.

Each of the sensor signals may include at least one piece of information about at least one area of the beam profile of the light beam. The photosensitive area 120 may be arranged so that the first sensor signal includes information about the first area of the beam profile, and the second sensor signal includes information about the second area of the beam profile. The first area of the beam profile and the second area of the beam profile may be adjacent or overlapping regions, or both. The first area of the beam profile and the second area of the beam profile may not exactly match in area.

The evaluation device 144 may be configured to determine and/or select a first area of the beam profile and a second area of the beam profile. The first area of the beam profile may include substantially edge information of the beam profile, and the second area of the beam profile may include substantially center information of the beam profile. The beam profile may have a center, i.e., a maximum value of the beam profile and/or a center point of the plateau of the beam profile and/or a geometric center of the light spot, and a trailing edge extending from the center. The second area may include an inner area of the cross section, and the first area may include an outer area of the cross section. Preferably, the center information has an edge information percentage of less than 10%, more preferably less than 5%, and most preferably, the center information does not include edge content. The edge information may include information from the entire beam profile, particularly the center and edge areas. The edge information has a center information percentage of less than 10%, preferably less than 5%, and more preferably, the edge information does not include center information. If the beam profile is near or around the center and substantially includes center information, at least one area of the beam profile may be determined and/or selected as the second area of the beam profile. If the beam profile includes at least a portion of the falling edge of the cross section, at least one area of the beam profile may be determined and/or selected as the first area of the beam profile. For example, the entire area of the cross section may be determined as the first region. The first area of the beam profile may be area A2, and the second area of the beam profile may be area A1. Similarly, the center signal and the edge signal may be determined by using a segment of the beam profile, such as a circular segment of the beam profile. For example, the beam profile may be divided into two segments by a secant or chord that does not pass through the center of the beam profile. Thus, one segment substantially includes edge information, and the other segment substantially includes center information. For example, the edge signal may be further subtracted from the center signal to further reduce the amount of edge information in the center signal.

The edge information may include information about the number of photons in a first area of the beam profile, and the center information may include information about the number of photons in a second area of the beam profile. The evaluation unit 144 may be configured to determine a surface integral of the beam profile. The evaluation unit 144 may be configured to determine the edge information by integration and/or summation of the first area. The evaluation unit 144 may be configured to determine the center information by integration and/or summation of the second area. For example, the beam profile may be a trapezoidal beam profile, and the evaluation unit may be configured to determine the integral value of the trapezoid. Furthermore, when a trapezoidal beam profile is assumed, the determination of the edge and center signals may be replaced by an equivalent evaluation that utilizes characteristics of the trapezoidal beam profile, such as the slope and position of the edges and the height of the central plateau, and derives the edge and center signals through geometric considerations.

Additionally or alternatively, the evaluation unit 144 may be configured to determine one or both of center and edge information from at least one slice or cut of the light spot. This may be achieved, for example, by replacing the surface integral of the combined signal Q with a line integral along the slice or cut. To improve accuracy, multiple slices or cuts through the light spot may be used and averaged. In the case of an elliptical spot profile, averaging over several slices or cuts may improve distance information.

For example, the evaluation device 144
a) determining at least one optical sensor 118 having the highest sensor signal and forming at least one center signal;
b) evaluating the sensor signals of the optical sensors 118 of the matrix 116 and forming at least one sum signal;
c) determining at least one combined signal by combining the center signal and the sum signal; and d) determining at least one vertical coordinate z of the selected feature by evaluating the combined signal.
The sensor signal may be evaluated by

For example, the center signal may be the signal of at least one photosensor 116 having the highest sensor signal among multiple sensor signals generated by photosensors 118 in the entire matrix 116 or in a region of interest within the matrix 116, which region of interest may be predetermined or determinable within the image generated by the photosensors of the matrix 116. The center signal may result from a single photosensor 118 or from a group of photosensors 118; in the latter case, by way of example, the sensor signals of the group of photosensors 118 may be added, integrated, or averaged to determine the center signal. The group of photosensors 118 from which the center signal results may be a group of adjacent photosensors, such as photosensors 118 that are less than a predetermined distance away from the actual photosensor with the highest sensor signal, or may be a group of photosensors that produce sensor signals within a predetermined range from the highest sensor signal. The group of photosensors 118 from which the center signal results may be selected to be as large as possible to allow for the largest dynamic range. The evaluation device 144 may be configured to determine the center signal by integrating multiple sensor signals, for example the sensor signals of multiple light sensors around the light sensor with the highest sensor signal.

The determination of the center signal may be performed electronically, since the comparison of sensor signals is fairly easy to implement with conventional electronics, or may be performed fully or partially by software. The detection of the center of the light spot, i.e., the detection of the center signal and/or the at least one optical sensor from which the center signal originates, may be performed fully or partially electronically, or may be performed fully or partially using one or more software algorithms. Specifically, the evaluation device 144 may comprise at least one center detector for detecting the at least one highest sensor signal and/or for forming the center signal. Specifically, the center detector may be embodied fully or partially in software and/or fully or partially in hardware. The center detector may be fully or partially integrated into at least one sensor element and/or embodied fully or partially independent of the sensor element.

Specifically, the center signal may be selected from the group consisting of: the highest sensor signal; the average of a group of sensor signals that are within a predetermined tolerance range of the highest sensor signal; the average of sensor signals from a group of optical sensors including the optical sensor 118 with the highest sensor signal and a predetermined group of adjacent optical sensors 118; the sum of sensor signals from a group of optical sensors 118 including the optical sensor 118 with the highest sensor signal and a predetermined group of adjacent optical sensors 118; the sum of a group of sensor signals that are within a predetermined tolerance range of the highest sensor signal; the average of a group of sensor signals that exceed a predetermined threshold; the sum of a group of sensor signals that exceed a predetermined threshold; the integral of sensor signals from a group of optical sensors 118 with the highest sensor signal and a predetermined group of adjacent optical sensors 118; the integral of a group of sensor signals that are within a predetermined tolerance range of the highest sensor signal; or the integral of a group of sensor signals that exceed a predetermined threshold.

For example, the sum signal can be derived by adding the sensor signals, integrating the sensor signals, or averaging the sensor signals of the entire matrix 116 or a region of interest within the matrix, which region of interest may be predetermined or determinable within the image generated by the optical sensors 118 of the matrix 116. When adding, integrating, or averaging the sensor signals, the actual optical sensors 118 from which the sensor signals are generated may be excluded from the summation, integration, or averaging, or may be included in the summation, integration, or averaging. The evaluation device 144 may be configured to determine the sum signal by integrating the signals of the entire matrix 116 or the signals of a region of interest within the matrix 116. Furthermore, if a trapezoidal beam profile is assumed, the determination of the edge and center signals can be replaced by an equivalent evaluation that utilizes characteristics of the trapezoidal beam profile, such as determining the slope and position of the edges and the height of the central plateau, and derives the edge and center signals through geometric considerations.

The sum signal can be derived from all sensor signals in the matrix 116 excluding the sensor signal resulting from the photosensor 118 that contributes to the center signal, from the sensor signals within the region of interest, or from one of these possibilities. In all cases, a reliable sum signal can be produced that can be reliably compared to the center signal to determine the vertical coordinate. In general, the sum signal may be selected from the group consisting of: an average of all sensor signals in the matrix 116; a sum of all sensor signals in the matrix 116; an integral of all sensor signals in the matrix 116; an average of all sensor signals in the matrix 116 excluding sensor signals from photosensors 118 contributing to the center signal; a sum of all sensor signals in the matrix 116 excluding sensor signals from photosensors 118 contributing to the center signal; an integral of all sensor signals in the matrix 116 excluding sensor signals from photosensors 118 contributing to the center signal; a sum of sensor signals of photosensors 118 within a predetermined range from the photosensor 118 with the highest sensor signal; an integral of sensor signals of photosensors 118 within a predetermined range from the photosensor 118 with the highest sensor signal; a sum of sensor signals that exceed a predetermined threshold of photosensors 118 located within a predetermined range from the photosensor 118 with the highest sensor signal; an integral of sensor signals that exceed a predetermined threshold of photosensors 118 within a predetermined range from the photosensor with the highest sensor signal. However, other options exist. The summation may be performed fully or partially in software and/or fully or partially in hardware. Summing is usually possible by purely electronic means that are easily implemented in detectors. Thus, in the field of electronics, summing devices are generally known that add two or more electronic signals, both analog and digital. Therefore, the evaluation device 144 may comprise at least one summing device for forming a sum signal. The summing device may be fully or partially integrated into the sensor element, or may be fully or partially embodied independently of the sensor element. The summing device may be fully or partially embodied in hardware or software, or both.

The combined signal may be a signal generated by combining the center signal and the sum signal. Specifically, the combining may include one or more of: forming a quotient of the center signal and the sum signal, or forming the inverse quotient; forming a quotient of a multiple of the center signal and a multiple of the sum signal, or forming the inverse quotient; forming a quotient of a linear combination of the center signals and a linear combination of the sum signal, or forming the inverse quotient. Additionally or alternatively, the combined signal may include any signal or combination of signals that includes at least one item of information related to a comparison between the center signal and the sum signal. The evaluation device 144 may be configured to determine at least one longitudinal coordinate z of the object using at least one known, determinable, or predetermined relationship between the sensor signals. In particular, the evaluation device 144 may be configured to determine at least one coordinate z of the object using at least one known, determinable, or predetermined relationship between a quotient signal derived from the sensor signals and a longitudinal coordinate.

The comparison between the center signal and the sum signal may be performed, in particular, by forming one or more quotient signals. Thus, in general, the combined signal may be a quotient signal Q derived by one or more of the following: forming a quotient of the center signal and the sum signal, or forming its inverse; forming a quotient of a multiple of the center signal and a multiple of the sum signal, or forming its inverse; forming a quotient of a linear combination of the center signals and a linear combination of the sum signal, or forming its inverse; forming a quotient of the center signal and a linear combination of the sum signal and the center signal, or forming its inverse; forming a quotient of the sum signal and a linear combination of the sum signal and the center signal, or forming its inverse; forming a quotient of a power of the center signal and a power of the sum signal, or forming its inverse. However, other options exist. The evaluation device 144 may be configured to form one or more quotient signals. The evaluation device 144 may further be configured to determine at least one vertical coordinate by evaluating at least one quotient signal.

The evaluation device 144 may be specifically configured to use at least one predetermined relationship between the combined signal Q and the vertical coordinate to determine at least one vertical coordinate. Thus, for the reasons disclosed above and due to the dependence of the light spot characteristics on the vertical coordinate, the combined signal Q is typically a monotonic function of the object's vertical coordinate and/or a monotonic function of the light spot size, such as the diameter or equivalent diameter of the light spot. Thus, by way of example, in the case where a linear light sensor is specifically used, the simple quotient Q = s _center / s _sum of the sensor signal s _center and the sum signal s _sum may be a monotonically decreasing function of distance. Without wishing to be bound by theory, this is believed to be due to the fact that, in the preferred configuration described above, both the center signal s _center and the sum signal s _sum decrease as a square function with increasing distance to the light source, due to the reduced amount of light reaching the detector. However, in the optical configuration used in the experiment, the center signal s _center decreases more rapidly than the sum signal s _sum because the light spot in the image plane increases and thus spreads over a wider area. The quotient of the center signal and the sum signal therefore decreases continuously with the increase in the diameter of the light beam or light spot on the photosensitive area of the light sensor of the matrix. Furthermore, the quotient is usually independent of the total power of the light beam, since the total power of the light beam forms a coefficient of both the center signal and the sum sensor signal. As a result, the combined signal Q may form a quadratic signal that provides a unique and clear relationship between the center signal and the sum signal and between the size or diameter of the light beam. On the other hand, since the size or diameter of the light beam depends on the distance between the object through which the light beam propagates towards the detector and the detector itself, i.e., on the longitudinal coordinate of the object, a unique and clear relationship may exist between the center signal and the sum signal, on the one hand, and between the center signal and the longitudinal coordinate, on the other hand. Regarding the latter, reference may be made to one or more of the above-mentioned prior art documents, such as WO 2014/097181 A1, for example. The predetermined relationship can be determined by analytical considerations, for example by assuming a linear combination of Gaussian light beams, and/or by empirical measurements, such as measurements of the combined signal and/or the center signal and sum signal or secondary signals derived therefrom, as a function of the longitudinal coordinate of the object.

The evaluation device 144 may be configured to use at least one predetermined relationship between the combined signal and the vertical coordinate. The predetermined relationship may be one or more of an empirical relationship, a semi-empirical relationship, and an analytically derived relationship. The evaluation device 144 may include at least one data storage device for storing the predetermined relationship, such as a lookup list or a lookup table.

Depth from photon ratio techniques enable reliable distance measurements with reduced computational demands, particularly reduced processing power, even in environments that cause multiple reflections from biased light sources or reflective measurement objects. The present invention enables identifying the material of a reflective object and estimating the distance to the projector 122 or sensor element 114, even when there are various materials located at various distances from the sensor element 114, or when the projector 122 produces nearly identical combinations of laser spot characteristics. Furthermore, the present invention enables estimating the orientation of a reflective surface and detecting edges. An illumination pattern 124 including spatially modulated illumination features 125 can make at least one characteristic or parameter of the resulting modulated illumination feature more robust to variations caused by the physical properties of the material of the reflective target object. This at least one characteristic or parameter may depend only on the distance between the reflective object 112 and the projector 122 or sensor element 114. Other characteristics or parameters of the illumination features 125 can be changed and modified to provide information about the type and physical properties of the reflective material and its distance to the projector 122 or sensor element 114. As outlined above, the illumination features 125 may be patterned illumination features, each of which includes multiple sub-features 141. The evaluation device 144 may be configured to determine information about the distance between the object 112 and the projector 122 and/or sensor element 114 by analyzing the patterned reflection features of the reflection image 142. The evaluation device 144 may be configured to locate and segment each patterned illumination feature. The evaluation device 144 may be configured to determine the center of each of the sub-features. The evaluation device 144 may be configured to determine the distance between the centers of the sub-features 141. The evaluation device 144 may be configured to determine information about the distance between the object 112 and the projector 122 and/or sensor element 114 from the distance between the centers of the sub-features 141 using a predetermined relationship. The evaluation device 144 may be configured to determine a corrected vertical coordinate z taking into account the determined distance between the object 112 and the projector 122 and/or the sensor element 114. The corrected vertical coordinate may be a vertical coordinate with improved accuracy.

The evaluation unit 144 may be configured for edge detection. The illumination feature 125 may include at least three sub-features 141. The evaluation unit 144 may be configured to determine the longitudinal coordinate of the object 112 for each of the sub-features 141 by evaluating the combined signal Q from the sensor signals of the respective sub-features 141. The evaluation unit 144 may be configured to determine the normal and local direction of the reflective surface of the object 112 from the longitudinal coordinate determined from the sub-features 141. Only one patterned illumination feature may be sufficient to enable the normal and local direction of the reflective surface to be estimated and to enable knowing whether the patterned laser spot has been reflected on an edge.

Furthermore, for problematic reflective surfaces, the probability of obtaining a usable laser spot reflection is higher when projecting such a dense cluster of spots compared to a relatively sparsely distributed single spot.

The present invention may enable improved performance of distance and depth measurements using depth from photon ratio techniques. This can be done through simple hardware modifications and simple computationally efficient additions to currently used algorithms. As a result, detector 110 can achieve better performance and be used for a number of additional applications.

The distances determined by the DPR technique provide distance estimates for each illumination feature and can be refined by triangulation using the known positions of the sensor element 114 and projector 122. To calculate the refined vertical coordinates using triangulation, a so-called correspondence problem must be solved. When using a regular pattern, such as a rectangular pattern, two adjacent points may be directly adjacent on the epipolar line. For a robust correspondence problem, the physical distance between the features of the pattern may be large so that the point density of the pattern is low. As outlined above, the present application proposes that the illumination features 125 be arranged in a periodic pattern with equidistant rows, where each row of illumination features has an offset, and the offsets of adjacent rows are different. The offsets enable reaching feature densities with large distances on the epipolar line, enhancing the robustness of the correspondence problem. The selection of the differential offset may be such that the structure of the illumination pattern 124 can be designed with respect to the field of view of the sensor element 114.

The evaluation device 144 may be configured to determine the longitudinal area of the selected reflection feature by evaluating the combined signal Q, the longitudinal area being given by the longitudinal coordinate z and an error interval ±ε. The error ε may depend on the measurement uncertainty of the optical sensor 118. The measurement uncertainty of the optical sensor 118 may be determined and/or estimated in advance and/or stored in at least one data storage unit of the evaluation device 144. For example, the error interval may be ±10%, preferably ±5%, more preferably ±1%.

The evaluation unit 144 may be configured to determine at least one displacement region in the at least one reference image corresponding to the vertical region. The reference image may be an image different from the reflected image, determined at a different spatial position compared to the reflected image 142. The reference image may be determined by one or more of recording at least one reference feature, imaging at least one reference feature, and calculating the reference image. The reference image and the reflected image may be images of an object determined at different spatial positions having a certain distance between them. The distance may be a relative distance, also referred to as a baseline. The evaluation unit 144 may be configured to determine at least one reference feature in the at least one reference image that corresponds to the at least one reflection feature. The evaluation unit 144 may be configured to perform image analysis and identify features in the reflected image 142. The evaluation unit 144 may be configured to identify at least one reference feature in the reference image having substantially the same vertical coordinate as the selected reflection feature. The reference feature corresponding to the reflection feature may be determined using epipolar geometry. For a description of epipolar geometry, see, for example, X. See, for example, "Dreidimensionales Computersehen" by Jiang, H. Bunke, Springer, Berlin Heidelberg, 1997. Epipolar geometry may assume that the reference image and the reflected image 142 are images of an object determined at different spatial positions and/or spatial orientations having a fixed distance between them. The reference image and the reflected image 142 may be images of the object 112 determined at different spatial positions having a fixed distance between them. The evaluation device 144 may be configured to determine an epipolar line 137 in the reference image. The relative positions of the reference image and the reflected image 142 may be known. For example, the relative positions of the reference image and the reflected image 142 may be stored in at least one storage unit of the evaluation device 144. The evaluation device 144 may be configured to determine a straight line extending from a selected reflection feature in the reflected image 142. The straight line may include a possible object feature corresponding to the selected feature. The lines and baselines define an epipolar plane. Because the reference image is determined at a different relative position than the reflected image, corresponding possible object features can be imaged on lines called epipolar lines 137 in the reference image. Thus, features of the reference image that correspond to selected features in the reflected image lie on the epipolar lines 137. Due to image distortion or changes in system parameters due to aging, temperature changes, mechanical stress, etc., the epipolar lines 137 may cross or be very close to each other, and/or the correspondence between the reference and reflected features may be unclear. Furthermore, each known location or object in the real world may be projected onto the reference image, or vice versa. The projection may be known by calibrating the detector 110, which corresponds to teaching-in the epipolar geometry of a particular camera.

Specifically, the displacement region can be a region in the reference image where a reference feature corresponding to a selected reflection feature is expected to be located in the reference image. Depending on the distance to the object 112, the image position of the reference feature corresponding to the reflection feature can be displaced in the reference image compared to the image position of the reflection feature in the reflection image. The displacement region can include only one reference feature. The displacement region can also include multiple reference features. The displacement region can include the epipolar line 137 or a portion of the epipolar line 137. The displacement region can include multiple epipolar lines 137 or multiple portions of multiple epipolar lines 137. The displacement region can extend along the epipolar line 137, or orthogonal to the epipolar line 137, or both. The evaluation unit 144 can be configured to determine the reference feature along the epipolar line 137 corresponding to the vertical coordinate z, and to determine the extent of the displacement region along the epipolar line 137 or orthogonal to the epipolar line corresponding to the error interval ±ε. Measurement uncertainty in distance measurements using the combined signal Q may result in a non-circular displacement region because the measurement uncertainty may vary with direction. Specifically, the measurement uncertainty along the epipolar line 137 or multiple epipolar lines 137 may be larger than the measurement uncertainty in an orthogonal direction relative to the epipolar line 137 or multiple epipolar lines 137. The displacement region may include a region extending in an orthogonal direction relative to the epipolar line 137 or multiple epipolar lines 137. The evaluation device may determine the displacement region around the image position of the reflection feature. The evaluation device 144 may be configured to determine a vertical coordinate z of the reflection feature and an error interval ±ε from the combined signal Q to determine the displacement region along the epipolar line 137 corresponding to z±ε. The evaluation device may be configured to match the selected reflection feature with at least one reference feature within the displacement region. Matching may include determining and/or evaluating corresponding reference features and reflection features. The evaluation unit 144 may be configured to match selected features of the reflection image with reference features within the displacement region by using at least one evaluation algorithm taking into account the determined vertical coordinate z. The evaluation algorithm may be a linear scaling algorithm. The evaluation unit 144 may be configured to determine an epipolar line 137 that is closest to and/or within the displacement region. The evaluation unit 144 may be configured to determine the epipolar line 137 that is closest to the image position of the reflection feature. The extent of the displacement region along the epipolar line 137 may be greater than the extent of the displacement region perpendicular to the epipolar line 137. The evaluation unit 144 may be configured to determine the epipolar line 137 before determining the corresponding reference feature. The evaluation unit 144 may determine a displacement region around the image position of each reflection feature. The evaluation unit 144 may be configured to assign an epipolar line 137 to each displacement region at each image position of the reflection feature, such as by assigning the epipolar line 137 closest to the displacement region, and/or the epipolar line 137 within the displacement region, and/or the epipolar line 137 closest to the displacement region along a direction perpendicular to the epipolar line. The evaluation unit 144 may be configured to determine a reference feature corresponding to the image position of the reflection feature by determining a reference feature closest to the assigned displacement region, and/or a reference feature within the assigned displacement region, and/or a reference feature closest to the assigned displacement region along the assigned epipolar line 137, and/or a reference feature within the assigned displacement region along the assigned epipolar line 137.

Additionally or alternatively, the evaluation device 144 performs the following steps:
- determining the displacement area of the image location of each reflective feature;
assigning epipolar lines 137 to the displacement region of each reflection feature, such as by assigning the epipolar line 137 closest to the displacement region and/or the epipolar line 137 within the displacement region and/or the epipolar line 137 closest to the displacement region along a direction perpendicular to the epipolar line;
- assigning and/or determining at least one reference feature to each reflection feature, such as by assigning a reference feature closest to the assigned displacement area and/or a reference feature within the assigned displacement area and/or a reference feature closest to the assigned displacement area along the assigned epipolar line 137 and/or a reference feature within the assigned displacement area along the assigned epipolar line 137;
may be configured to perform

Additionally or alternatively, the evaluation device 144 may be configured to determine between multiple epipolar lines 137 and/or reference features to be assigned to a reflection feature, such as by comparing the distances of the reflection features and/or epipolar lines 137 in the reference image and/or by comparing error-weighted distances, such as ε-weighted distances, of the reflection features and/or epipolar lines 137 in the reference image and assigning the epipolar line 137 and/or reference feature with the shorter distance and/or ε-weighted distance to the reference feature and/or reflection feature.

Preferably, the detector 110 can be configured to pre-classify selected reflection features using the combined signal Q so that they can be unambiguously assigned to a single reference feature. In particular, the illumination features 125 of the illumination pattern 124 can be positioned such that corresponding reference features in the reference image have as large a relative distance from each other as possible on the epipolar line.

The evaluation unit 144 may be configured to determine the displacement of the matched reference feature and the selected reflection feature. The evaluation unit 144 may be configured to determine the vertical information of the matched feature using a predetermined relationship between the vertical coordinate and the displacement. For example, the vertical information may be a distance value. The evaluation unit 144 may be configured to determine the predetermined relationship by using triangulation. If the position of the selected reflection feature and the position of the matched reference feature in the reflection image and/or the relative displacement of the selected reflection feature and the matched reference feature are known, the vertical coordinate of the corresponding object feature may be determined by triangulation. Thus, the evaluation unit 144 may be configured to select a reflection feature, for example, for each successive and/or row, and to determine a corresponding distance value using triangulation for each potentially possible position of the reference feature. The displacement and the corresponding distance value may be stored in at least one storage unit of the evaluation unit 144. The evaluation device 144 may include at least one data processing device, such as, by way of example, at least one processor, at least one DSP, at least one FPGA, and/or at least one ASIC. Furthermore, at least one data storage device may be provided to store at least one predetermined or determinable relationship between the vertical coordinate z and the displacement, such as by providing one or more look-up tables for storing the predetermined relationship. The evaluation device 144 may be configured to store parameters for intrinsic and/or extrinsic calibration of the camera and/or detector 110. The evaluation device 144 may be configured to generate parameters for intrinsic and/or extrinsic calibration of the camera and/or detector, such as by performing a Tsai camera calibration. The evaluation unit 144 may be configured to calculate and/or estimate parameters such as the focal length of the transfer device, the distortion coefficient of the radiation lens, the coordinate of the center of distortion of the radiation lens, a scale factor to account for uncertainties due to imperfections in the scanning and digitization hardware timing, the rotation angle of the transformation between world coordinates and camera coordinates, the translation component of the transformation between world coordinates and camera coordinates, the aperture angle, the image sensor type, the principal point, the skew factor, the camera center, the camera orientation, the baseline, the rotation or translation parameters of the camera and/or illumination source, the aperture, and the focal length.

Using the combined sensor signals allows for the estimation of distances, such as the vertical coordinate z within an error interval. By determining the displacement region corresponding to the estimated vertical coordinate and the corresponding error interval, the number of possible solutions along the epipolar line can be significantly reduced. The number of possible solutions can even be reduced to one. The determination of the vertical coordinate z and the error interval can be performed during pre-evaluation before matching the selected reflection feature with the reference feature. This can reduce computational requirements, thus significantly reducing costs and enabling use in mobile or outdoor devices. Furthermore, triangulation systems typically require a large baseline to detect large distances. Pre-evaluating the vertical coordinate z and the error interval using the combined sensor signals and then matching the selected reflection feature with the reference feature can allow for the use of a short baseline, thus providing a compact device. Furthermore, pre-evaluating the vertical coordinate z and the error interval using the combined sensor signals and then matching the selected reflection feature with the reference feature can improve accuracy and/or speed and/or reduce computational requirements compared to conventional triangulation systems. Additionally, the number of illumination features, such as the number of illumination points in an illumination pattern, may be reduced to increase the light intensity at each illumination point to compete with ambient light while complying with eye safety regulations. In conventional triangulation systems, reducing the number of illumination features may increase the difficulty of matching reflected features with reference features. Additionally, the number of illumination features, such as the number of illumination points in an illumination pattern, may be increased to increase the resolution of the resulting depth map without increasing the processing power of the evaluation device 144, such as in mobile applications, for example, to increase the resolution of distance measurements.

110 Detector 112 Object 114 Sensor element 116 Matrix 118 Light sensor 120 Light sensitive area 122 Projector 124 Illumination pattern 125 Illumination feature 126 Laser source 128 DOE
130 Opening 132 Housing 134 Collection optics 136 Control unit 137 Epipolar line 138 Reflection pattern 139 Field of view 140 Transfer device 141 Subfeature 142 Reflection image 144 Evaluation device

Claims (8)

A detector (110) for determining the position of at least one object (112), said detector (110) comprising:
at least one projector (122) for illuminating said object (112) with at least one illumination pattern (124), said illumination pattern (124) comprising a plurality of illumination features (125), said illumination features (125) being spatially modulated such that said illumination features (125) are patterned illumination features; and
at least one sensor element (114) having a matrix (116) of optical sensors (118), each having a light-sensitive area (120), each optical sensor (118) designed to generate at least one sensor signal in response to illumination of its respective light-sensitive area (120) by a reflected light beam propagating from the object to the detector (110), said sensor element (114) being configured to determine at least one reflected image (142);
at least one evaluation device (144), configured to select at least one reflection feature of the reflection image (142), the reflection feature being a feature in an image plane generated by the object (112) in response to illumination by at least one illumination feature (125), the evaluation device (144) configured to determine at least one longitudinal coordinate z of the selected reflection feature of the reflection image (142) by using a depth from photon ratio technique by evaluating a combined signal Q from the sensor signals, the combined signal Q being a signal generated by combining the sensor signals, the evaluation device (144) configured to derive the combined signal Q by one or more of dividing the sensor signals, dividing a multiple of the sensor signals, dividing a linear combination of the sensor signals, and the evaluation device (144) configured to use at least one predetermined relationship between the combined signal Q and the longitudinal area to determine a longitudinal area,
each of the patterned illumination features (125) comprises a plurality of sub-features (141) , and the evaluation device (144) is configured to determine information regarding the distance between the object (112) and the projector (122) by analyzing the patterned reflection features of the reflection image (142), the evaluation device (144) is configured to find and segment each patterned reflection feature, the evaluation device (144) is configured to determine the center of each of the sub-features (141), the evaluation device (144) is configured to determine the distance between the centers of the sub-features (141), and the evaluation device (144) is configured to determine information regarding the distance between the object (112) and the projector (122) from the distance between the centers of the sub-features (141) using a predetermined relationship; and/or
The illumination features (125) are arranged in a periodic pattern with equal distances d in rows, each row of the illumination features (125) having an offset, the offsets of adjacent rows being different , and the coefficient δ of the offsets being:
where a and b are integers;
The detector ( 110) wherein adjacent rows of said illumination features (125) are offset by δ·d, where δ is an offset coefficient and d is the distance between adjacent illumination features (125) arranged in said rows . The detector (110) of claim 1, wherein the projector (122) comprises at least one light source configured to generate at least one light beam, and the projector (122) comprises at least one transfer device configured to diffract and replicate the light beam to generate the illumination pattern (124) including patterned illumination features (125). A detector (110) as described in claim 1 or 2, wherein the projector (122) comprises at least one array of light sources arranged in a specific pattern and configured to generate a cluster of light beams, and the projector (122) comprises at least one transfer device for diffracting and replicating the cluster of light beams to generate an illumination pattern (124) including the patterned illumination features (125). 2. The detector (110) of claim 1, wherein the evaluation device (144) is configured to determine a corrected vertical coordinate z taking into account a determined distance between the object ( 112 ) and the projector (122). Detector (110) according to any one of claims 1 to 4 , wherein the sensor elements (114) and the projector (122) are positioned such that the rows are parallel to an epipolar line (137). 6. The detector of claim 1, wherein the evaluation device is configured to determine a longitudinal area of the selected reflection feature by evaluating the combined signal Q, the longitudinal area being given by the longitudinal coordinate z and an error interval ±ε, the evaluation device is configured to determine at least one displacement area in at least one reference image corresponding to the longitudinal area, the reference image being a different image from the reflection image determined at a different spatial position compared to the reflection image, the evaluation device is configured to match the selected reflection feature with at least one reference feature in the displacement area, the evaluation device is configured to determine a displacement of the matched reference feature and the selected reflection feature, and the evaluation device is configured to determine the longitudinal information of the matched reference feature using a predetermined relationship between the longitudinal information and the displacement . A method for determining the position of at least one object (112) by using a detector (110) according to any one of claims 1 to 6 , comprising the following method steps:
- illuminating the object (112) with at least one illumination pattern generated by at least one projector (122) of the detector (110), wherein the illumination pattern (124) comprises a plurality of illumination features (125), the illumination features (125) being spatially modulated, the illumination features (125) being patterned illumination features (125), each of the patterned illumination features (125) comprising a plurality of sub-features (141), and/or the illumination features (125) being arranged in a periodic pattern equidistant in rows, each of the rows of the illumination features (125) having an offset, the offsets of adjacent rows being different;
generating, in response to illumination, at least one sensor signal for each reflected light beam incident on a light-sensitive area (120) of said light sensors (118) of a sensor element (114) having a matrix (116) of said light sensors (118);
- determining at least one reflected image (142) using said sensor element (114);
- selecting at least one reflection feature of said reflection image (142) and evaluating said sensor signals using at least one evaluation device (144) to thereby determine at least one vertical coordinate z of said selected reflection feature, said evaluation comprising evaluating a combined signal Q from said sensor signals;
A method comprising: Use of a detector (110) according to any one of claims 1 to 6 referring to a detector, the use being selected from the group consisting of position determination in traffic technology, entertainment applications, security applications, surveillance applications, safety applications, human machine interface applications, logistics applications, tracking applications, outdoor applications, mobile applications, communication applications, photography applications, machine vision applications, robotics applications, quality control applications, manufacturing applications.